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*  f 


COURSE  OF  INSTRUCTION 


IN 


ORDNANCE  AND  GUNNERY: 


COMPILED  FOR  THE  USE  OF  THE 


CADETS 


OF   THE 


UNITED  STATES  MILITARY  ACADEMY. 


Capt.  J.  G.  BENTON,  Oed.  Dept., 

LATE   INSTRUCTOR   OF   ORDNANCE   AND   SCIENCE   OF  GUNNERY,   MILITARY  ACADEMY,   WEST  POINT, 
PRIN.   AS9T.    TO   TIIE   CHIEF   OF   ORDNANCE,    U.  S.  A. 


SECOND   EDITION,    REVISED    AND   ENLARGED. 


or  thc 
UNIVERSITY 

^LlfORH^y     KEW  YORK: 

D.  VAN  NOSTRAND,  192    BROADWAY. 
1862. 


v 


1 


pK 


Entered  according  to  Act  of  Congress,  in  the  year  1 862, 

By   D.   VAN  NOSTRAND, 

In  the  Clerk's  Office  of  the  District  Court  of  the  United  States  for  the 
Southern  District  of  New  York. 


C.    A.    AI.VORD,    KLECTROTYPER   AND   PRINTER. 


A  large  portion  of  the  matter  contained  in  the  following 
pages,  and  particularly  that  which  relates  to  the  "  Effects  of 
Gunpowder''  and  the  "  Motion  of  Projectiles  in  fire-arms" 
is  taken  from  Piobert's  Cours  oV Artillerie. 


70 


CONTENTS. 


CHAPTER  I.  Page. 

Gunpowder 7 

CHAPTER  II. 
Projectiles 71 

CHAPTER  III. 
Cannon 104 

CHAPTER  IV. 
Artillery  Carriages 212 

CHAPTER  Y. 
Machines  and   Implements 248 

CHAPTER  YI. 
Small-Arms 270 

CHAPTER  YII. 
Ptrotechny 342 

CHAPTER  YIII. 
Science  of  Gunnery . 382 

CHAPTER  IX. 
Loading,  Pointing  and  Discharging   Fire- Arms 435 

CHAPTER  X. 
Different  Kinds  of  Fires 450 

CHAPTER  XL 
Effects  of  Projectiles 471 

CHAPTER  XII. 
Employment  of  Artillery 488 

CHAPTER  XIII. 

Tables  of  Multipliers 505 

Tables  of  Fire 516 

APPENDIX. 525 

INDEX 537 


ORDNANCE    AND    GUNNERY. 

PART    I. 

ee  £ 

CHAPTER    I. 

GUNPOWDER. 

1.  General  theory.  Gunpowder  and  the  compositions 
of  pyrotechny  are  the  means  used,  in  modern  warfare, 
to  propel  projectiles,  explode  mines,  destroy  ships  and 
buildings,  and  furnish  light  and  signals  for  the  opera- 
tions of  an  army  at  night.  They  are  simply  mechanical 
mixtures  of  substances  which  give  out  light,  heat,  and 
gas  in  their  combustion,  or  chemical  union  with  each 
other. 

The  two  classes  of  substances  generally  used  for  these 
purposes  are  the  nitrates  and  chlorates  on  one  hand,  and 
charcoal,  sulphur,  antimony,  &c,  on  the  other.  The 
former  class  contains  a  large  amount  of  oxygen,  which 
is  a  strong  supporter  of  combustion ;  and  the  latter  em- 
braces those  substances  which  have  a  powerful  affinity 
for  it. 

Explosion  is  a  phenomenon  arising  from  the  sudden 
enlargement  of  the  volume  of  a  body,  as  in  the  case  of 
combustion,  when  a  solid  body  is  rapidly  converted 
into  one  of  vapor  or  gas.     If  this  change  of  state  be 

t 


8  GUNPOWDER. 

accompanied  by  the  development  of  a  large  amount  of 
heat,  the  explosive  effect  will  be  very  much  increased. 

Gunpowder  is  an  explosive  substance,  formed  by  the 
mechanical  mixture  of  nitrate  of  potassa,  sulphur,  and 
charcoal. 

The  parts  performed  by  these  ingredients  in  the  ex- 
plosion will  be  best  understood  by  an  examination  of 
the  following  table  : 


COMPOSITION   OF   GUNPOWDER. 

AFTE] 

3  carbonic  acid  (gas). 


BEFORE   COMBUSTION.  AFTER   COMBUSTION. 

3  parts  of  carbon,  3  carbon, 

6  oxygen, 
1  part  of  nitrate  of  potassa,  -J  1  nitrogen,        1  nitrogen  (gas). 


•<ii 


potassium, 


1  part  of  sulphur,  1  sulphur, 


\  1  sulphide  of  potassium  (solid). 


A  gunpowder  can  be  made  of  nitrate  of  potassa  and 
charcoal  alone;  but  it  is  not  so  strong  as  when  sul- 
phur is  present ;  besides,  the  substance  of  the  grain  is 
friable,  has  considerable  affinity  for  moisture,  and  rapidly 
fouls  the  arms  in  which  it  is  used. 

Theoretically,  sulphur  does  not  contribute  directly  to 
the  explosive  force  of  gunpowder  by  furnishing  materi- 
als for  gas ;  but,  by  uniting  with  the  potassium,  it  affords 
a  large  amount  of  heat,  and  prevents  the  carbonic  acid 
from  uniting  with  the  potassa  and  forming  a  solid  com- 
pound— the  carbonate  of  potassa.  It  is  to  the  heat  and 
carbonic  acid  thus  formed  that  gunpowder  mainly  owes 
its  explosive  force. 

The  strength  of  gunpowder,  or  amount  of  work  which 
a  certain  quantity  is  capable  of  performing  in  a  given 
time,  depends  on  the  mass  of  the  powder  and  the  veloc- 
ity with  which  its  gaseous  particles  are  evolved. 

t 


SALTPETRE.  9 

This  velocity  of  evolution  of  the  gaseous  particles,  or 
"  quickness,"  depends  on  the  purity,  proportion,  and  in- 
corporation of  the  ingredients,  and  on  the  size,  form, 
and  density  of  the  grains.  These  will  be  discussed  in 
the  following  pages,  under  the  heads  of  Materials,  Fab- 
rication, Mechanical  Effects,  and  Chemical  Properties 
of  gunpowder. 

MATERIALS. 

SALTPETKE. 

2.  Description.  Saltpetre,  nitre,  or  nitrate  of  potassa, 
is  composed  of  53.45  of  nitric  acid,  and  46.55  of  potas- 
sa, or  KO+JSTO$.  It  crystallizes  in  colorless  six-sided 
prisms ;  has  a  cooling,  saline,  and  slightly  bitter  taste, 
and  deflagrates  with  more  violence  than  any  other 
nitrate  when  thrown  on  burning  charcoal.  It  is  an- 
hydrous ;  but  its  crystals  often  contain  water  mechan- 
ically confined.  It  is  not  deliquescent  in  common  air 
(a  very  important  quality  in  an  ingredient  of  gunpow- 
der), but  is  so  in  an  atmosphere  nearly  saturated  with 
moisture.     It  is  insoluble  in  the  oils  and  pure  alcohol. 

It  is  decomposed  when  strongly  heated,  and  oxygen 
is  evolved  at  first ;  finally  nitrogen  is  given  off,  and  per- 
oxyde  of  potassium  remains.  When  heated  with  com- 
bustible materials,  nitre  is  completely  deprived  of  its 
oxygen ;  it  is  consequently  much  used  as  an  oxydizing 
agent.     This  is  the  part  which  it  plays  in  gunpowder. 

The  solubility  of  nitre  increases  rapidly  with  the  tem- 
perature. 

100  parts  of  water  at  32°  dissolve  13.32  of  nitre. 
"  "  "  64.4°     "      29.00         " 

"  "  "        113°        "      74.00         " 

M  m  u         212o        u     246.15         " 


10  GUNPOWDER. 

Hence,  a  hot  saturated  solution,  on  cooling,  deposits 
the  greater  portion  of  the  salt  which  had  dissolved. 

3.  Sources.  Nitrate  of  potassa,  in  connection  with 
more  or  less  of  the  nitrates  of  lime  and  magnesia,  is  ob- 
tained from  several  sources,  among  which  may  be  enu- 
merated calcareous  caves,  certain  soils  in  warm  climates, 
artificial  nitre  beds,  and  the  mortar  of  stables  or  other 
buildings  long  occupied  by  animals,  in  which  cases  it 
generally  occurs  as  an  efflorescence.  It  is  also  found  in 
the  tobacco,  sunflower,  beet-root,  cornstalk,  and  other 
plants. 

The  caves  occurring  in  certain  porous  limestones  are 
often  found  to  contain  large  quantities  of  the  nitrates  of 
lime,  potassa,  and  magnesia,  deposited  in  the  loose  ma- 
terials at  the  bottom,  efflorescing  from  the  sides,  or  even 
contained  in  the  pores  of  the  rock  itself.  Many  of  the 
limestone  caves  in  Kentucky,  Virginia,  Tennessee,  <fcc, 
abound  in  nitrates.  In  Madison  county,  Kentucky, 
there  is  a  cave  1,936  feet  long  by  40  wide,  which  con- 
tains the  nitrates  of  potassa  and  lime,  mingled  with  the 
earthy  matter  at  the  bottom.  One  bushel  of  the  earth 
yields,  by  double  decomposition  with  carbonate  of  po- 
tassa, from  three  to  ten  pounds  of  nitre. 

The  greater  part  of  the  nitre  used  in  England,  and 
this  country,  is  derived  from  the  soil  in  various  parts  of 
the  East  Indies.  It  occurs  in  the  same  manner  in  vari- 
ous warm  countries,  as  Egypt,  Spain,  &c.  In  the  vicin- 
ity of  Monclova,  Mexico,  it  occurs  in  veins,  or  mines,  in 
a  state  of  great  purity. 

It  appears  to  be  generated  spontaneously  at  the  depth 
where  the  soil  retains  its  moisture ;  and  when  dissolved 
by  rains,  the  subsequent  evaporation,  by  capillary  at- 


SOUKCES    OF   NITEE.  1L 

traction,  causes  it  to  rise  to  the  surface,  where  it  is  de- 
posited as  a  crust. 

To  obtain  nitre  from  this  source,  the  earth  is  removed 
to  a  certain  depth,  and  treated  with  water,  which  dis- 
solves the  soluble  salts.  The  solution  is  then  transfer- 
red to  large  reservoirs,  when  it  soon  evaporates  by  solar 
heat,  and  deposits  large  crystals  of  nitre.  This  is 
known  in  commerce  as  rough,  or  crude  saltpetre.  The 
mother  waters  are  rejected;  but  as  they  contain  a  large 
quantity  of  the  nitrates  of  lime  and  magnesia,  they 
might  still  afford  some  nitre  if  they  were  mixed  with 
salts  of  potassa. 

In  the  north  of  Europe,  where  nitre  does  not  occur 
as  a  natural  product,  various  artificial  processes  have 
long  been  employed  to  obtain  it ;  and  similar  methods 
were  much  used  in  France  during  the  Revolution,  when 
that  country  could  not  be  supplied  from  Spain  and 
other  countries.     The  nitre-beds  were  mostly  used. 

Nitre-beds.  These  were  made  by  placing  loosely  on 
a  floor  of  wood  or  clay,  a  layer,  of  three  or  four  feet 
thick,  of  a  mixture  of  earth,  calcareous  matter — such  as 
marls,  calcareous  sands,  mortar  from  stables,  &c,  and 
various  animal  products — such  as  blood,  urine,  stable 
manure,  &c.  Vegetable  matter  was  found  to  be  useful, 
probably  furnishing  potassa.  The  whole  was  placed 
under  a  shed,  and  occasionally  moistened  with  addi- 
tional quantities  of  blood  or  urine,  and  in  about  two 
years  it  was  fit  for  lixiviation.  In  Prussia,  the  materials 
are  placed  in  parallel  walls  about  seven  feet  high,  and 
three  or  four  feet  thick,  which  arrangement  is  found  to 
be  more  convenient,  and  to  occupy  less  space  than 
the  beds. 


12  GUNPOWDER. NITRE. 

Mortar  exposed  to  decomposing  animal  matter,  in 
moist,  warm  places,  becomes  considerably  charged  with 
nitrates.  In  consequence,  the  mortar  in  old  stables  is 
often  found  to  be  rich  in  nitrates,  and  may  be  used  to 
obtain  nitre  directly,  or  it  may  be  advantageously 
mixed  with  the  materials  for  nitre-beds. 

The  lye  of  nitrified  substances  contains  nitrate  of 
potassa,  but  especially  nitrates  of  lime  and  magnesia; 
and  also  chlorides  of  sodium  and  calcium.  The  nitrates 
of  lime  and  magnesia  may  be  converted  into  nitrate  of 
potassa  by  means  of  the  carbonate  of  potassa ;  but  on 
account  of  the  increased  value  of  this  substance,  the 
process  now  generally  adopted  is  as  follows,  viz. :  first, 
the  nitrates  of  lime  and  magnesia  are  converted  into 
the  nitrate  of  soda,  by  means  of  the  sulphate  of  soda, 
and  then  by  the  chloride  of  potassium,  the  nitrate  of 
soda  is  converted  into  the  nitrate  of  potassa. 

The  nitrate  of  potassa  thus  obtained,  like  that  ob- 
tained from  the  soils  of  warmer  climates,  is  called  rough 
saltpetre,  and  contains  from  15  to  25  per  cent,  of  foreign 
matter,  principally  chlorides  of  sodium  and  potassium. 
These  are  separated  by  the  process  of  refining. 

4.  Refining.     The  refining  of  nitre  is  founded  on  its 
rapidly-increasing  solubility  with  elevation  of  tempera- 
ture, while  the  solubility  of  the  chlorides  of  sodium  and 
potassium  is  nearly  uniform.     (For  the  details  of  this- 
process  see  Ordnance  Manual.) 

If,  after  nitre  has  been  refined,  it  be  desired  to  pre- 
serve it  for  future  use,  it  is  fused  in  iron  pots,  and  cast 
into  cakes  weighing  about  seventy  pounds.  This  method 
has  the  advantage  of  reducing  its  volume,  and  expelling 
the  water   of  crystallization ;   but   it  requires  a  little 


TEST    OF   PURE   SALTPETRE. 

more  work  to  pulverize  it  afterward  in  making  gun- 
powder. 

As  the  United  States  are  in  a  great  measure  depen- 
dent on  the  East  Indies  for  this  important  material  of 
war,  it  has  been  the  policy  of  the  government  to  pur- 
chase yearly  a  certain  quantity  of  rough  saltpetre,  refine 
and  fuse  it,  and  store  it  away  in  the  arsenals  for  future 
use.  The  quantity  now  on  hand  in  the  arsenals 
amounts  to  several  millions  of  pounds. 

5.  Tests.  The  test  of  rough  saltpetre  is  founded  on 
the  fact  that  a  solution  of  nitrate  of  potassa,  saturated 
at  a  certain  temperature,  may  be  left  in  contact  with  an 
additional  quantity  of  saltpetre  at  the  same  tempera- 
ture, without  sensibly  dissolving  any  of  it ;  while  under 
the  same  circumstances  it  can  dissolve  sea  salt,  and 
many  other  soluble  salts. 

To  a  pound  of  rough  saltpetre  add  a  pint  of  water, 
saturated  with  pure  saltpetre ;  stir  the  mixture  for  ten 
minutes  with  a  glass  rod,  and  decant  the  liquor  on  a 
filter;  wash  the  saltpetre  a  second  time  in  the  same 
manner,  with  half  a  pint  of  the  saturated  solution,  and 
pour  the  whole  on  the  filter ;  let  it  drain,  and  then  dry 
it  perfectly  by  placing  it  first  on  a  bed  of  some  absor- 
bent matter,  such  as  ashes  or  lime,  and  then  by  evapora- 
tion in  a  glass  vessel  over  a  gentle  fire.  The  saturated 
solution  having  taken  up  only  the  foreign  salts,  what 
remains  on  the  filter  (allowing  two  per  cent,  for  earthy 
matter  and  the  saltpetre  left  by  the  saturated  water), 
is  the  quantity  of  pure  saltpetre  contained  in  the  pound 
of  rough.  As  the  changes  of  temperature  during  the 
operation  may  affect  the  quantity  of  pure  saltpetre  re- 
maining on  the  filter,  it  is  proper  to  perform  a  corre- 


14       GUNPOWDER. CHLOEATE  OF  POTASS  A. 

sponding  operation  at  the  same  time  and  under  the 
same  circumstances,  on  a  like  quantity  of  pure  salt- 
petre ;  the  gain  or  loss  thus  ascertained  will  show  the 
correction  to  be  made  in  the  former  result. 

Test  of  pure  saltpetre.  For  powder,  saltpetre  should 
not  contain  more  than  l-3000th  of  chlorides.  To  test 
this,  dissolve  200  grains  of  saltpetre  in  the  least  possi- 
ble quantity  (say  1,000  grains)  of  distilled  water ;  pour 
on  it  20  grains  of  the  solution  of  nitrate  of  silver, 
containing  10  grains  of  the  nitrate  to  1,033  grains  of 
water,  that  being  the  quantity  required  to  decompose 
200-3000ths  of  a  grain  of  muriate  of  soda ;  filter  the 
liquid  and  divide  it  into  two  portions ;  to  one  portion 
add  a  few  drops  of  the  solution  of  the  nitrate  of  silver; 
if  it  remains  clear,  the  saltpetre  does  not  contain  more 
than  l-3000th  of  muriate  of  soda ;  to  the  other  portion 
add  a  small  portion  of  the  solution  of  the  muriate  of 
soda ;  if  it  becomes  clouded,  the  saltpetre  contains  less 
than  l-3000th.  By  using  the  test  liquor  in  very  small 
quantities,  the  exact  proportion  of  muriate  of  soda  may 
be  ascertained.  At  the  refinery  of  Paris  it  does  not 
exceed  l-18,000th  of  the  saltpetre;  and  this  degree  of 
purity  is  attained  also  at  the  refinery  of  Messrs.  Du- 
pont.  Saltpetre  for  the  best  sporting  powder  is  refined 
a  second  time,  and  contains  not  more  than  l-60,000th 
part  of  chlorides. 

6.  Chlorate  of  Potassa.  Other  oxydizing  substances, 
such  as  the  chlorate  of  potassa  and  nitrate  of  soda,  may 
be  used  in  the  manufacture  of  gunpowder ;  but  for  this 
purpose,  they  are  inferior  to  the  nitrate  of  potassa.  The 
chlorate  of  potassa  is  a  substance  which  parts  with  its 
oxygen  easily,  and  makes  a  powder,  which  has  been 


NATURE    OF   CHARCOAL.  15 

found  by  experience,  to  give  at  least  double  the  range 
with  the  mortar  eprouvette,  of  that  made  with  nitrate 
of  potassa,  but  from  its  great  quickness,  resembles  the 
fulminates  in  its  destructive  effects  on  the  gun.  Besides, 
it  is  more  costly  than  nitrate  of  potassa,  renders  the 
powder  liable  to  explode  by  slight  causes,  and  gives  a 
residue  which  rapidly  corrodes  iron. 

Its  use  in  the  laboratory  is  chiefly  confined  to  the 
preparation  of  colored  fires  and  cannon  primers. 

The  nitrate  of  soda  is  found  as  an  extensive  deposit 
in  the  soils  of  some  portions  of  Peru  and  northern 
Mexico.  It  is  cheaper  than  nitrate  of  potassa,  and  for 
the  same  weight  affords  a  greater  amount  of  nitric  acid, 
or  oxygen.  Its  affinity  for  moisture  constitutes  a  serious 
objection  to  its  use  in  the  manufacture  of  a  gunpowder 
for  war  purposes,  or  one  that  is  to  be  preserved  for 
any  length  of  time. 

The  nitrate  of  soda  may  be  used  in  obtaining  the 
nitrate  of  potassa  by  decomposing  it  with  carbonate  of 
potassa — the  potash  of  commerce. 

CHARCOAL. 

7.  Nature  of  charcoal.  Charcoal  is  the  result  of 
the  incomplete  combustion  or  distillation  of  wood.  Its 
composition  and  properties  vary  with  the  nature  of  the 
wood,  and  mode  of  distillation  employed. 

Charcoal  obtained  from  light  wood  is  the  best  for 
gunpowder,  as  it  is  more  combustible  and  easy  to  pul- 
verize, and  contains  less  earthy  matters. 

Willow  and  poplar  are  used  for  this  purpose  in  the 
United  States,  and  the  black  alder  in  Europe.  The 
wood  must  be  sound,  and  should  not  be  more  than  three 


16  GUNPOWDER. CHARCOAL. 

or  four  years  old,  and  about  one  inch  in  diameter; 
branches  larger  than  this  should  be  split  up.  It  is  cut 
in  the  spring,  when  the  sap  runs  freely,  and  is  imnie" 
diately  stripped  of  its  bark.  The  smaller  branches  are 
used  for  fine  sporting  powder. 

The  operation  of  charring  may  be  performed  in  pits, 
but  the  method  now  almost  universally  used  in  making 
charcoal  for  gunpowder  is  that  of  distillation.  For  this 
purpose  the  wood  is  placed  in  an  iron  vessel,  generally 
of  a  cylindrical  form,  to  which  a  cover  is  luted;  an 
opening  with  a  pipe  is  made  to  conduct  off  the  gaseous 
products,  and  the  wood  is  thus  exposed  to  the  heat  of 
a  furnace.  The  progress  of  distillation  is  judged  of  by 
the  color  of.  the  flame  and  smoke,  and  sometimes  by 
test-sticks,  which  are  introduced  through  tubes  prepared 
for  the  purpose. 

8.  Properties.  The  charcoal  thus  obtained  should 
retain  a  certain  degree  of  elasticity,  and  should  have  a 
brown  color,  the  wood  not  being  entirely  decomposed ; 
it  retains  the  fibrous  appearance  of  the  wood,  and  the 
fracture  is  iridescent.  As  it  readily  absorbs  l-20th 
of  its  weight  of  moisture,  which  diminishes  its  inflam- 
mability, it  should  be  made  only  in  proportion  as  it  is 
required  for  use.  Wood  generally  contains  52  per  cent, 
of  carbon,  but  distillation  furnishes  not  more  than  30  to 
40  per  cent,  of  charcoal. 

The  specific  gravity  of  charcoal  triturated  under 
heavy  rollers,  is  about  1-380 ;  but  in  sticks,  as  it  comes 
from  the  charring  cylinders,  it  rarely  exceeds  .300. 

The  properties  of  charcoal  vary  much  with  the 
temperature  employed  in  the  preparation.  If  wood  be 
merely  heated  until  it  ceases  to  give  off  vapor,  a  true 


ACCIDENTS. 


17 


charcoal  is  obtained ;  but  by  raising  the  temperature 
to  redness  or  whiteness,  its  properties  will  be  much 
changed,  as  is  shown  in  the  following  table : 


1 

When  not  heated  to 
redness. 

Heated  to  redness        Heated  to  whiteness. 

For  electricity, 

"     heat. 
Combustibility. 

Non-conductor. 
Very  bad  conductor. 
Easy. 

Good  conductor. 
Good  conductor. 
Less  easy. 

Excellent  conductor. 
Excellent  conductor. 
Difficult. 

If  sufficient  heat  be  applied  to  drive  off  all  the  vola- 
tile matters  in  six  hours,  a  black  charcoal,  containing 
from  28  to  33  per  cent,  of  carbon,  will  be  obtained.  If 
the  heat  be  reduced  so  as  to  prolong  the  distillation  to 
twelve  hours,  the  charcoal  will  have  a  yellowish  brown 
color,  and  will  contain  from  38  to  40  per  cent,  of  car- 
bon. 

Charcoal  inflames  at  about  460°  Fahrenheit.  A 
black  coal  strongly  calcined  takes  fire  quickly,  but  is 
easily  extinguished.  A  brown  charcoal  takes  fire 
slowly,  but  burns  strongly  and  rapidly.  As  it  is  desir- 
able to  have  charcoal  for  gunpowder  very  combustible, 
it  must  therefore  be  prepared  at  a  low  temperature,  and 
must  be  light.  In  distillation,  the  heat  is  kept  below 
redness. 

9.  Accidents.  When  recently  prepared  charcoal  is 
pulverized  and  laid  in  heaps,  it  is  liable  to  absorb  oxy- 
gen with  such  rapidity  as  to  cause  spontaneous  combus- 
tion. This  has  been  the  cause  of  serious  accidents  at 
powder-mills;  and  hence  it  is  important  not  to  pul- 
verize charcoal  until  it  has  been  exposed  to  the  air  for 
several   days.      In   Prussian   powder-mills,    pulverized 


15  GUNPOWDER. CHAECOAL. 

charcoal  is  kept  in  a  fireproof  room,  in  iron  vessels,  as 
a  precaution  against  accidents. 

When  charcoal  has  not  absorbed  moisture,  and  is 
mixed  with  oxydizing  substances,  it  may  be  inflamed 
by  violent  shocks,  or  by  friction.  This  is  the  principal 
cause  of  the  accidents  which  occur  in  the  preparation 
of  explosive  mixtures  which  contain  charcoal. 

10.  Combustibility.  For  the  purpose  of  comparing 
the  combustibility  of  charcoals  made  of  different  mate- 
rials, a  certain  quantity  of  each  is  thoroughly  mixed 
with  nitre,  in  the  proportion  of  1  part  of  the  former  to 
5  of  the  latter,  and  driven  compactly  into  an  iron  tube 
about  .25  inches  in  diameter;  the  weight  and  length  of 
the  filled  tube  are  taken,  and  the  duration  of  the  com- 
bustion is  ascertained  by  a  pendulum  or  chronometer. 
The  length  of  composition  burned  in  a  second  of  time 
is  called  the  velocity  of  combustion,  and  is  taken  as  the 
measure  of  the  combustibility  of  that  particular  kind 
of  charcoal.  The  amount  of  residue  is  ascertained  by 
subtracting  the  weight  of  the  tube  and  residue  after 
burning  from  that  of  the  filled  tube  before  burning, 
and  again  subtracting  this  difference  from  the  weight 
of  the  composition  originally  in  the  tube.  The  velocity 
of  combustion  is  independent  of  the  diameter  of  the 
tube  and  of  the  material  of  which  it  is  made ;  but  it 
varies  slightly  with  the  pressure  used  in  driving  the 
composition,  and  very  much  with  the  degree  of  tritura- 
tion of  the  materials.  The  following  tables  contain 
some  of  the  results  thus  obtained,  viz. : 


COMBUSTIBILITY    OF    CHAKCOAL. 


19 


60  parts  of  nitre  and  12  of  charcoal. 
Black  Charcoals. 

Velocity  of  com- 
bustion. 

Percentage  of 
residue. 

Charcoal  of  Hemp, 

.31  inch. 

16.6 

"            Grape  Vine,   . 

.26     " 

27.7 

Pine,. 

.18     « 

41.6 

"           Black  Alder, . 

.16     " 

33.3 

"           Spindle  Tree,      . 

.15     " 

37.5 

"           Hazel,    . 

.13     " 

41.6 

"           Chestnut,    . 

.14     " 

50.0 

"           Walnut, 

.11     " 

45.8 

Coke. 

.06     " 

62.5 

"           Sugar,    . 
Charcoal  made  by  distilling  Black 
Alder,  and  conducted  so   as  to 

.04     " 

66.6 

give, 
For  100  p'ts  wood,  40  p'ts  charcoal, 

.14  inch. 

39.0 

"              il        30              " 

.16     " 

37.0 

25               «* 

.15     " 

33.3 

"               "         15               " 

.12     " 

35.0 

The  following  table  shows  the  influence  of  trituration 
lcI  proportion  of  ingredients  : 


Mixture. 

Parts  of 

charcoal 

t.»  60  of 

nitre. 

Charcoal  made  of  Hemp. 

Charcoal  made  of  Pine. 

6  hours1  trituration. 

4  hours'  trituration. 

6  hours' 
trituration. 

4  hours' 
trituration. 

Velocity. 

Perct.  of 
residue. 

58.0 
45.0 
16.6 
13.0 
12.0 
11.0 

Velocity. 

Pr.  ct  of 
residue. 

Velocity. 

Velocity. 

1 

8 
! 
7 
1 
6" 
1 
5 
JL 
4 
1 
3 
1 
2 

si- 
io 

12 
15 
20 
30 
60 

.10  in. 

.12 

.31 

.39 

.56 

.65 

.14 

.08  in. 
.10 

.17 

.27 

55.0 
43.0 
26.0 
17.0 

.09  in. 

.15 

.18 

.35 

.39 

.59 

.07  in. 

.09 

.12 

.20 

.27 

.53 

20  GUNPOWDER. SULPHITE. 


SULPHUR. 


11.  Properties.  Pure  sulphur  is  of  a  citron-yellow 
color,  and  shining  fracture ;  it  crackles  when  pressed  in 
the  hand.  The  specific  gravity  of  native  sulphur  is 
2.033;  that  of  sulphur  refined  by  sublimation  1.900; 
its  specific  gravity  is  diminished  by  trituration.  When 
heated,  it  melts  at  226°  into  a  thin,  amber-colored  liquid; 
if  the  temperature  be  then  raised  to  about  400°  it  be- 
comes dark  and  thick;  but  if  heated  still  further,  up  to 
601°,  its  boiling  point,  it  becomes  again  thin  and  limpid. 
It  begins  to  pass  off  in  vapor  at  115°,  and  if  heated 
rapidly,  inflames  at  370°.  It  is  insoluble  in  water,  but 
soluble  in  oils  and  slightly  so  in  alcohol. 

Sulphur  is  generally  found  in  great  quantities  in  the 
neighborhood  of  volcanoes;  it  may  also  be  obtained 
from  metallic  ores  (pyrites)  and  other  sources.  Most 
of  that  used  in  the  United  States  comes  from  Sicily 
through  the  French  refineries. 

Crude  sulphur,  as  extracted  by  the  first  sublimation 
from  the  ore,  contains  about  8  per  cent,  of  earthy  mat- 
ter. It  is  purified  by  a  second  sublimation,  from  which 
it  is  collected  in  the  form  of  powder,  called  the  flowers 
of  sulphur  j  or,  it  is  melted  and  run  into  moulds,  mak- 
ing roll  brimstone.  It  may  be  also  refined,  but  not  so 
thoroughly,  by  being  simply  melted  and  skimmed. 

Pure  sulphur  is  entirely  consumed  in  combustion; 
and  its  purity  is  thus  easily  tested  by  burning  about 
100  grains  in  a  glass  vessel;  the  residue  should  not  ex- 
ceed a  small  fraction  of  a  grain. 


MANUFACTURE  21 

MANUFACTURE  OF  GUNPOWDER. 

12.  Proportions  of  ingredients. 

Nitre.       Charcoal.    Sulphur 

By  the  atomic  theory,     .     .     74.64     13.51     11.85 

(NOi+KO)  +  sa+ '-& 

In  the  United  States: 
For  military  service,    .     .     .     76.00     14.00     10.00 
For  blasting  and  mining,     .     62.00     18.00     20.00 

The  proportions  of  the  ingredients  of  the  earliest 
gunpowder  known,  differ  but  slightly  from  those  now 
in  use;  and  these,  it  will  be  seen,  nearly  agree  with 
those  called  for  by  the  theory  of  combining  equivalents. 

For  the  general  purposes  of  artillery,  slight  varia- 
tions in  the  proportions  of  the  ingredients  for  powder 
are  not  found  to  affect  its  strength;  but  for  blasting  or 
mining  purposes,  a  slower  powder  is  found  to  answer 
nearly  as  well  as  a  quick  one,  consequently  the  propor- 
tion of  nitre  is  reduced  much  below  that  of  gunpowder. 
Blasting  powder  is  thus  made  cheap;  but  as  it  leaves  a 
large  amount  of  residuum,  it  cannot  be  advantageously 
used  in  fire-arms. 

13.  Operations.  The  several  operations  of  fabrica- 
ting gunpowder  are: 

1st.  Pulverizing ;  which  consists  in  reducing  the 
ingredients  to  finely  divided  dust. 

2d.  Incorporating;  which  consists  in  bringing  the 
particles  of  this  dust  into  such  intimate  contact  that 
each  particle  of  powder  shall  be  composed  of  one  of 
each  of  the  ingredients. 

3d.  Compressing ;  which  gives  strength  and  density 
to  the  substance  of  the  powder,  by  converting  the  in* 


22  GUNPOWDER. MANUFACTURE. 

corporated  mixture  into  a  cake  which 'will  not  crumble 
in  transportation. 

4th.  Graining ;  which  breaks  up  the  cake  into  small 
fragments  or  grains,  and  increases  the  surface  of  com- 
bustion. 

5th.  Glazing ;  which  hardens  the  surface,  to  protect 
it  from  the  action  of  moisture,  and  rounds  the  sharp 
angles  of  the  grains  to  prevent  the  formation  of  dust 
in  transportation. 

6th.  Drying;  which  frees  the  powder  from  the 
moisture  introduced  in  certain  operations  of  the  fabri- 
cation. 

7th.  Dusting ;  which  frees  it  from  the  dust,  which 
would  otherwise  fill  up  the  interstices  and  retard  the 
inflammation  of  the  charge. 

The  proportions  of  the  ingredients,  as  well  as  the 
art  of  making  gunpowder,  vary  in  different  countries, 
and  even  among  the  different  manufactories  of  the  same 
country. 

The  variations  in  the  proportions  are  slight,  how- 
ever, and  the  differences  in  the  modes  of  manufacture 
are  principally  confined  to  the  more  important  opera- 
tions of  pulverizing,  mixing,  and  conrpressing  the  com- 
position. For  French  military  powder,  these  operations 
are  performed  in  the  "pounding-mill,"  or  a  series  of 
mortars  and  pestles.  In  Prussia  the  composition  is 
pressed  into  cake  by  passing  it  between  two  heavy  rol- 
lers, by  means  of  an  endless  band  of  cloth,  which  re- 
ceives the  dust  from  a  hopper.  In  England  these 
operations  are  performed  by  the  "rolling-barrel,"  "cyl- 
inder-mill," and  "press."  The  superior  strength  and 
excellent  preservative  qualities  of  the  English  powder 


MANUFACTURE.  23 

have  led  to  the  adoption  of  this  mode  of  manufacture 
in  the  United  States. 

14.  Proce§§e§  of  manufacture.*  The  buildings  in 
which  the  different  operations  are  carried  on  are  sepa- 
rated from  each  other,  and  protected  by  trees  or  trav- 
erses as  far  as  practicable. 

Pulverizing.  The  saltpetre  is  usually  pulverized 
sufficiently  when  it  comes  from  the  refinery.  The  char- 
coal is  placed  in  large  cast-iron  barrels  with  twice  its 
weight  of  zinc  balls.  The  barrel  has  several  ledges  on 
the  interior,  and  is  made  to  revolve  from  20  to  25  times 
in  a  minute.  It  is  pulverized  in  2  or  3  hours.  The 
sulphur  is  placed  in  barrels  made  of  thick  leather 
stretched  over  a  wooden  frame,  with  twice  its  weight  of 
zinc  balls  from*3  to^  inches  in  diameter,  and  the  barrel 
made  to  revolve  about  20  times  per  minute.  It  takes 
one  hour  to  pulverize  the  sulphur. 

Incorporating.  The  ingredients  having  been  weigh- 
ed out  in  the  proportions  above  given,  the  charcoal  and 
sulphur  are  put  together  in  a  rolling-barrel  similar  to 
that  in  which  the  sulphur  is  pulverized,  and  rolled  for 
one  hour.  The  saltpetre  is  then  added,  and  rolled  for 
three  hours  longer.  In  some  mills  this  operation  is 
omitted.  It  is  now  taken  to  the  cylinder,  or  rolling- 
mill.  This  consists  of  two  cast-iron  cylinders  rolling 
round  a  horizontal  axis  in  a  circular  trough  of  about  4 
feet  diameter,  with  a  cast-iron  bottom.  The  cylinders 
are  6  feet  in  diameter,  18  inches  thick  on  the  face,  and 
weigh  about  8  tons  each.  They  are  followed  by  a 
wooden  scraper,  which  keeps  the  composition  in  the 
centre  of  the  trough. 

*  Vide     Ordnance  Manual. 


24  GUNPOWDER. MANUFACTURE. 

A  charge  of  75  lbs.  in  some  mills,  and  150  lbs.  in 
others,  is  then  spread  in  the  trough  of  the  rolling-mill, 
and  moistened  with  2  to  3  per  cent,  of  water,  according 
to  the  hygrometric  state  of  the  atmosphere. 

It  is  rolled  slowly  at  first,  and  afterward  from  8  to 
10  revolutions  of  the  roller  per  minute,  for  1  hour  for 
50  lbs.,  and  3  hours  for  150  lbs.  of  composition.  A 
little  water  is  added,  as  the  process  advances,  if  the 
composition  gets  very  dry — which  is  judged  of  by  its 
color. 

When  the  materials  are  thoroughly  incorporated, 
the  cake  is  of  a  uniform,  lively,  grayish,  dark  color.  In 
this  state  it  is  called  mill-cake. 

The  quality  of  the  powder  depends  much  on  the 
thorough  incorporation  of  the  materials,  and  burns 
more  rapidly  as  this  operation  is  more  thoroughly  per- 
formed. 

The  mill-cake  is  next  taken  to  the  press-house,  to  be 
pressed  into  a  hard  cake. 

Pressing.  The  mill-cake  is  sprinkled  with  about  3 
per  cent,  of  water,  and  arranged  in  a  series  of  layers 
about  4  inches  thick,  separated  by  brass  plates.  A  pow- 
erful pressure  is  brought  to  bear  on  the  layers,  which 
are  subjected  to  the  maximum  pressure  for  about  10  to 
15  minutes,  when  it  is  removed.  Each  layer  is  thus 
formed  into  a  hard  cake  about  an  inch  thick. 

Granulating.  The  cake  is  broken  into  pieces  by  means 
of  iron-toothed  rollers  revolving  in  opposite  directions, 
their  axes  being  parallel  and  the  distance  between  them 
regulated  as  required.  Fluted  rollers  are  sometimes  used. 
The  pieces  are  passed  through  a  succession  of  rollers, 
each  series  being  closer  together,  by  which  the  pieces 


MANUFACTURE.  25 

are  broken  into  others  still  smaller,  which  pass  over  a 
sieve  to  another  roller,  the  small  grains  passing  through 
the  sieve  into  a  receiver  below,  until  the  whole  is  re- 
duced to  the  required  size.  The  various-sized  grains  are 
separated  by  the  sieves  between  the  different  rollers. 

Glazing.  Several  hundred  pounds  of  the  grained 
powder,  containing  from  3  to  4  per  cent,  of  water, 
are  placed  in  the  glazing  barrel,  which  is  made  to  re- 
volve from  9  to  10  times  per  minute,  and  in  some 
mills  from  25  to  30  times  per  minute.  Usually  ffom 
10  to  12  hours  are  required  to  give  the  required  glazing. 
In  this  operation  the  sharp  angles  are  broken  off,  there- 
by diminishing  the  dust  produced  in  transportation, 
and  the  surface  of  the  grain  receives  a  bright  polish. 

Drying.  The  powder  is  spread  out  on  sheets  stretch- 
ed upon  frames  in  a  room  raised  to  a  temperature  of 
140°  to  180°  by  steam-pipes  or  by  a  furnace.  The  tem- 
perature should  be  raised  gradually,  and  should  not 
exceed  180°,  ventilation  being  kept  up. 

Dusting.  The  powder  is  finally  sifted  through  fine 
sieves,  to  remove  all  dust  and  fine  grains. 

15.  Round  powder.  In  case  of  emergency,  and 
when  powder  cannot  be  procured  from  the  mills,  it  may 
be  made,  in  a  simple  and  expeditious  manner,  as  fol- 
lows :  Fix  a  powder-barrel  on  a  shaft  passing  through 
its  two  heads,  the  barrel  having  ledges  on  the  inside; 
to  prevent  leakage,  cover  it  with  a  close  canvas  glued 
on,  and  put  the  hoops  over  the  canvas.  Put  into 
the  barrel  10  lbs.  of  sulphur  in  lumps,  and  10  lbs.  of 
charcoal,  with  60  lbs.  of  zinc  balls  or  of  small  shot 
(down  to  No.  4,  0.014  in.  in  diameter  nearly);  turn 
it,  by  hand  or  otherwise,  30  revolutions  in  a  minute. 


26  GUNPOWDER. MANUFACTURE. 

To  10  lbs.  of  this  mixture  thus  pulverized,  add  30  lbs. 
of  nitre,  and  work  it  two  hours  with  the  balls ;  water 
the  40  lbs.  of  composition  with  2  quarts  of  water, 
mixing  it  equally  with  the  hands,  and  granulate  with 
the  graining-sieve.  The  grains  thus  made,  not  being 
pressed,  are  too  soft.  To  make  them  hard,  put  them 
into  a  barrel  having  5  or  6  ledges  projecting  about 
0.4  in.  inside ;  give  it  at  first  8  revolutions  in  a  min- 
ute, increasing  gradually  to  20.  The  compression  will 
be  proportionate  to  the  charge  in  the  barrel,  which 
should  not,  however,  be  more  than  half  full ;  continue 
this  operation  until  the  density  is  such  that  a  cubic 
foot  of  the  powder  shall  weigh  855  oz.,  the  mean  den- 
sity of  round  powder  ;  strike  on  the  staves  of  the  bar- 
rel from  time  to  time,  to  prevent  the  adhesion  of  the 
powder. 

Sift  the  grains  and  dry  the  powder  as  usual.  That 
which  is  too  fine  or  too  coarse  is  returned  to  the  pulver- 
izing-barrel. 

This  powder  is  round,  and  the  grain  is  sufficiently 
hard  on  the  surface,  but  the  interior  is  soft,  which  makes 
it  unfit  for  keeping,  and  may  cause  it  to  burn  slowly. 
This  defect  may  be  remedied  by  making  the  grains  at 
first  very  small,  and  by  rolling  them  on  a  sheet  or  in  a 
barrel,  watering  them  from  time  to  time,  and  adding 
pulverized  composition  in  small  proportions ;  in  this 
way,  the  grains  will  be  formed  by  successive  layers ; 
they  are  then  separated  according  to  size,  glazed  and 
dried. 

It  appears  from  experiments  that  the  simple  incorpo- 
ration of  the  materials  makes  a  powder  which  gives 
nearly  as  high  ranges  with  cannon  as  grained  powder. 


INSPECTION,    PROOF,    ETC. 


The  incorporated  dust  from  the  rolling-barrel  may  be 
used  in  case  of  necessity. 

INSPECTION,  PROOF,  ETC. 

16.  Proving  instruments  Before  powder  for  the 
military  service  is  received  from  the  manufacturer,  it  is 
inspected  and  proved.  For  this  purpose,  at  least  50 
barrels  are  thoroughly  mixed  together.  One  barrel  of 
this  is  proved  by  firing  three  rounds  from  a  musket, 
with  service-charge,  if  it  be  musket  powder ;  if  cannon 
or  mammoth  powder,  from  an  8-inch  columbiad,  with 
10  lbs.  and  a  solid  shot  of  65  lbs.  weight  and  7.88  inches 
in  diameter ;  if  it  be  mortar  powder,  from  an  8-inch 
mortar,  with  1.25  lb.  and  a  shell  7.88  inches  in  diameter, 
weighing  47.5  lbs.  The  general  character  of  the  grain, 
and  its  freedom  from  dust,  are  noted. 

General  Qualities.  Gunpowder  should  be  of  an  even- 
sized  grain,  angular  and  irregular  in  form,  without 
sharp  corners,  and  very  hard.  When  new,  it  should 
leave  no  trace  of  dust  when  poured  on  the  back  of  the 
hand,  and  when  flashed  in  quantities  of  10  grains  on  a 
copper  plate,  it  should  leave  no  bead  or  foulness.  It 
should  give  the  required  initial  velocity  to  the  ball,  and 
not  more  than  the  maximum  pressure  on  the  gun,  and 
should  absorb  but  little  moisture  from  the  air. 

Size  of  grain.  The  size  of  the  grain  is  tested  by 
standard  sieves  made  of  sheet  brass  pierced  with  round 
holes.  Two  sieves  are  used  for  each  kind  of  powder — 
Nos.  1  and  2  for  mortar,  3  and  4  for  musket,  5  and  6  for 
cannon  powder. 

Diameter  of  holes  for  mortar-powder  :  No.  1,  0.1  inch; 


28  GUNPOWDER. 

No.  2,  0.07  inch.  For  musket-powder  :  No.  3,  0.06  inch; 
No.  4,  0.035  inch.  For  cannon-powder:  No.  5,  0.31 
inch;  No.  6,  0.27  inch. 

Mortar-powder.  All  should  pass  through  sieve  No.  1 ; 
none  through  No.  2. 

Musket-potvder.  All  should  pass  through  No.  3,  and 
none  through  No.  4. 

Cannon-powder.  All  should  pass  through  No.  5,  and 
none  through  No.  6. 

Gravimetric  density.  Is  the  weight  of  a  given  meas- 
ured quantity.  It  is  usually  expressed  by  the  weight 
of  a  cubic  foot  in  ounces. 

This  cannot  be  relied  upon  for  the  true  density  when 
accuracy  is  desired,  as  the  shape  of  the  grain  may  make 
the  denser  powder  seem  the  lighter. 

Specific  gravity.  The  specific  gravity  of  gunpow- 
der must  be  not  less  than  1.75 ;  and  it  is  important  that 
it  should  be  determined  with  accuracy.  Alcohol  and 
water  saturated  with  saltpetre  have  been  used  for 
this  purpose ;  but  they  do  not  furnish  accurate  results. 
Mercury,  only,  is  to  be  relied  upon. 

Mercury  densimeter.  This  apparatus  was  invented 
by  Colonel  Mallet,  of  the  French  army,  and  M.  Bianchi, 
and  consists  of  an  open  vessel  containing  mercury, 
a  frame  supporting  a  glass  globe  communicating  by 
a  tube  with  the  mercury  in  the  open  vessel,  and  joined 
at  top  to  a  graduated  glass  tube,  which  communi- 
cates by  a  flexible  tube  with  an  ordinary  air-pump. 
Stop-cocks  are  inserted  in  the  tubes  above  and  below 
the  glass  globe,  and  a  diaphragm  of  chamois-skin  is 
placed  over  the  orifice  at  the  bottom  of  the  globe, 
and  one  of  wire-cloth  over  the  upper  orifice. 


29 

The  operation  consists  as  follows:  Fill  the  globe 
with  mercury  to  any  mark  of  the  graduated  tube,  by 
means  of  the  air-pump ;  close  the  stop-cocks ;  detach 
the  globe,  full  of  mercury,  and  weigh  it ;  empty  and 
clean  the  globe;  introduce  into  it  a  given  weight  of 
gunpowder ;  attach  the  globe  to  the  tubes ;  exhaust 
the  air  till  the  mercury  fills  the  globe  and  rises  to 
the  same  height  as  before;  shut  the  stop-cocks;  take 
off  the  globe  and  weigh  it  as  before.  If  we  represent 
by  a  the  weight  of  the  powder  in  the  globe,  by  P 
the  weight  of  the  globe  full  of  mercury,  by  P'  the 
weight  of  the  globe  containing  the  powder  and  mer- 
cury, and  by  D  the  specific  gravity  of  the  mercury. 

The  specific  gravities  of  the  powder  and  the  mer- 
cury being  proportional  to  the  weights  of  equal  volumes 
of  these  two  substances,  we  have 

aiP-P'+a:  :d:B 

hence  ^=— — ■= 

P— P'+a 

A  mean  of  two  or  three  results  will  give  the  true 
specific  gravity. 

The  density  of  some  samples  of  powder  has  been 
brought  up  to  1.831. 

Initial  velocity.  The  initial  velocity  is  determined 
by  means  of  the  Ballistic  Pendulum,  or  by  Captain  Ben- 
ton's Electro-Ballistic  Pendulum.  For  the  method  of 
using  this  machine,  see  section  408. 

The  standard  initial  velocities  of  the  different  pow- 
ders remain  to  be  determined. 

Strain  upon  the  gun.  This  is  determined  by  Cap- 
tain Rodman's  pressure-piston,  which  will  be  explained 
hereafter. 


J 


30  GUNPOWDEK. INSPECTION,    ETC. 

Mortar-powder  should  not  give  a  greater  pressure 
than  Jft/zn^ounds  on  the  square  inch. 

Cannon-powder  should  not  give  a  greater  pressure 
than ■-■:•;.."?? pounds  on  the  square  inch. 

Inspection  report.  The  report  of  inspection  should 
show  the  place  and  date  of  fabrication  and  of  proof,  the 
hind  of  powder  and  its  general  qualities,  as  the  number 
of  grains  in  100  grs.,  whether  hard  or  soft,  round  or  an- 
gular, of  uniform  or  irregular  size,  and  if  free  from  dust 
or  not ;  the  initial  velocities  obtained  in  each  fire ;  the 
amount  of  moisture  absorbed ;  and,  finally,  the  height 
of  the  barometer  and  hygrometer  at  the  time  of  proof. 

17.  Packing.  Government  powder  is  packed  in  bar- 
rels of  100  lbs.  each.  The  barrels  are  made  of  well- 
seasoned  white  oak ;  and  hooped  with  hickory  or  cedar 
hoops,  which  should  be  deprived  of  their  bark  to  ren- 
der them  less  liable  to  be  attacked  by  worms.  Barrels 
made  of  corrugated  tin  are  undergoing  trial,  to  test 
their  fitness  to  replace  those  made  of  wood. 

Maries  on  tlie  barrels.  Each  barrel  is  marked  on 
both  heads  (in  white  oil-colors,  the  head  painted  black) 
w^ith  the  number  of  the  barrel,  the  name  of  the  manu- 
facturer, year  of  fabrication,  and  the  kind  of  powder, — 
cannon,  (used  for  heavy  cannon,)  mortar,  (used  for  mor- 
tars and  field  cannon,)  or  musket — the  mean  initial  ve- 
locity, and  the  pressure  per  square  inch  on  the  pressure- 
piston.  Each  time  the  powder  is  proved,  the  initial  ve- 
locity is  marked  below  the  former  proofs  and  the  date 
of  the  trial  opposite  it. 

18.  Analysis.  Whatever  may  be  the  mode  of  proof 
adopted,  it  is  essential,  in  judging  of  the  qualities  of 
gunpowder,  to  know  the  mode  of  fabrication  and  the 


ANALYSIS.  91 

proportions  and  degree  of  purity  of  the  materials.  The 
latter  point  may  be  ascertained  by  analysis. 

In  the  first  place,  determine  the  quantity  of  water 
that  the  powder  contains,  by  subjecting  it  to  a  temper- 
ature of  212°,  in  a  stove  or  in  a  tube  with  a  current  of 
warm  air  passing  over  it,  until  it  no  longer  loses  in 
weight.  The  difference  in  weight,  before  and  after  dry- 
ing, gives  the  amount  of  moisture  contained  in  the 
powder. 

To  determine  the  quantity  of  saltpetre.  In  a  vessel 
of  tinned  copper,  like  a  common  coffee-pot,  dissolve 
1,000  grains  of  powder,  well  dried  before  weighing,  in 
2,000  grains  of  distilled  water,  and  heat  it  until  it  boils; 
let  it  stand  a  moment,  and  then  decant  it  on  a  piece  of 
filtering-paper,  doubled  exactly  in  the  middle;  repeat 
this  operation  four  times;  at  the  fourth  time,  instead  of 
decanting,  pour  the  whole  contents  of  the  vessel  on  the 
filter;  drain  the  filter^  and  wash  it  several  times  with 
2,000  grains  of  water  heated  in  the  vessel,  using  in  all 
these  operations  10,000  grains  of  water.  After  passing 
through  the  filters,  this  water  contains  in  solution  all 
the  saltpetre,  the  quantity  of  which  is  ascertained  by 
evaporating  to  dryness.  Dry  the  double  filter  with  the 
mixture  of  coal  and  sulphur,  and  take  the  weight  of 
this  composition  by  using  the  exterior  filter  to  ascertain 
the  weight  of  that  on  which  the  composition  remains; 
this  weight  serves  to  verify  that  of  the  saltpetre  and  to 
estimate  the  loss  in  the  process. 

To  determine  the  quantity  of  charcoal  directly.  To 
separate  the  sulphur  from  the  charcoal,  subject  the 
powder,  either  directly  or  after  the  saltpetre  has  been 
dissolved  out,  to  the  action  of  a  boiling  solution  of  the 

CTa  R  a  * 
'  or  THE 

UNIVERSITY 


32  GUNPOWDER.- 

sulphide  of  potassium  or  sodium,  which  dissolves  the 
sulphur  and  leaves  the  charcoal,  the  weight  of  which 
may  be  easily  determined. 

It  is  important  that  the  sulphides  of  potassium  and 
sodium  used  in  dissolving  the  sulphur,  should  contain 
no  free  potassa  or  soda;  for  each  of  these  alkalies  would 
dissolve  a  part  of  the  carbon — particularly  of  the 
brown  coal. 

The  sulphide  of  carbon  also  dissolves  the  sulphur 
contained  in  powder,  and  may  be  used  to  determine  the 
weight  of  charcoal  which  it  contains. 

The  charcoal,  separated  from  the  saltpetre  and  sul- 
phur, is  dried  with  care  and  weighed,  and  should  then 
be  submitted  to  analysis  in  an  apparatus  used  for  burn- 
ing organic  matters.  The  composition  of  the  charcoal 
may  be  judged  of  by  comparing  it  with  the  results  ob- 
tained in  the  analysis  of  charcoal  of  known  quality 
used  in  the  manufacture  of  powder. 

To  determine  the  quantity  cf  sulphur  directly.  Mix 
and  beat  in  a  mortar  10  grains  of  dry  powder,  10  of 
subcarbonate  of  potash,  10  of  saltpetre,  and  40  of 
chloride  of  sodium ;  put  this  mixture  in  a  vessel  (cap- 
sule) of  platinum  or  glass,  on  live  coals,  and,  when  the 
combination  of  the  materials  is  completed  and  the  mass 
is  white,  dissolve  it  in  distilled  water,  and  saturate  the 
solution  with  nitric  acid ;  decompose  the  sulphate  which 
has  been  formed,  by  adding  a  solution  of  chloride  of 
barium,  in  which  the  exact  proportions  of  the  water 
and  the  chloride  are  known.  According  to  the  atomic 
proportions,  the  quantity  of  sulphur  will  be  to  that  of 
the  chloride  of  barium  used  as  20.12  to  152.44. 

19.   Hygrometric  qualities.   The  susceptibility  of  pow- 


EESTOEATION.  33 

der  to  absorb  moisture  is  due  to  the  charcoal  and  the 
presence  of  deliquescent  salts,  principally  chloride  of 
sodium  or  common  salt.  The  absorbent  power  may  be 
judged  of  by  exposing  1  lb.  to  the  air  in  a  moist  place 
(such  as  a  cellar  which  is  not  too  damp)  on  a  glazed 
earthen  dish,  for  15  or  20  days,  stirring  it  sometimes  so 
as  to  expose  the  surface  better;  the  powder  should  be 
previously  well  dried,  at  the  heat  of  about  140°.  Well- 
glazed  powder,  made  of  pure  material,  treated  in  this 
way,  will  not  increase  in  weight  more  than  5  parts  in 
1,000,  or  a  half  of  one  per  cent. 

20.  Quickness  of  burning.  The  relative  quickness 
of  two  different  powders  may  be  determined  by  burn- 
ing a  train  laid  in  a  circular  or  other  groove  which  re- 
turns into  itself,  one  half  of  the  groove  being  filled  with 
each  kind  of  powder,  and  fire  communicated  at  one  of 
the  points  of  meeting  of  the  two  trains;  the  relative 
quickness  is  readily  deduced  from  observation  of  the 
point  at  which  the  flames  meet. 

21.  Restoring  unserviceable  powder.  When  the 
quantity  of  water  does  not  exceed  7  per  cent.,  the  pow- 
der may  be  restored  by  drying ;  this  may  be  effected  in 
the  magazine,  if  it  be  dry,  by  means  of  ventilation,  or 
by  the  use  of  the  chloride  of  calcium  for  twenty  or 
thirty  days. 

Quick-lime  may  be  used ;  but  the  use  of  it  is  attend- 
ed with  danger;  on  account  of  the  heat  evolved  in 
slaking. 

When  powder  has  absorbed  from  7  to  12  per  cent, 
of  water,  it  may  still  be  restored  by  drying  in  the  sun 
or  drying-house;  but  it  remains  porous  and  friable,  and 
unfit  for  transportation :  in  this  case  it  is  better  to  work 

3 


34  GUNPOWDER. PRESERVATION. 

it  over.  In  service,  it  may  be  worked  by  means  of  the 
rolling-barrels,  as  described  for  making  round  powder. 
When  powder  has  been  damaged  with  salt  water, 
or  become  mixed  with  dirt  or  gravel,  or  other  foreign 
substances  which  cannot  be  separated  by  sifting,  or 
when  it  has  been  under  water,  or  otherwise  too  much 
injured  to  be  reworked,  it  must  be  melted  down  to  ob- 
tain the  saltpetre  by  solution,  nitration,  and  evaporation. 

22.  storage,  &c.  In  the  powder-magazines,  the  bar- 
rels are  generally  placed  on  the  sides,  three  tiers  high, 
or  four  tiers  if  necessary ;  small  skids  should  be  placed 
on  the  floor,  and  between  the  several  tiers  of  barrels, 
in  order  to  steady  them ;  and  chocks  should  be  placed 
at  intervals  on  the  lower  skids,  to  prevent  the  rolling 
of  the  barrels.  The  powder  should  be  separated  ac- 
cording to  its  kind,  the  place  and  date  of  fabrication, 
and  the  proof  range.  Fixed  ammunition,  especially  for 
cannon,  should  not  be  put  in  the  same  magazine  with 
powder  in  barrels,  if  it  can  be  avoided. 

Besides  being  recorded  in  the  magazine  book,  each 
parcel  of  powder  should  be  inscribed  on  a  ticket  attach- 
ed to  the  pile,  showing  the  entries  and  the  issue. 

23.  Pre§ervation.  For  the  preservation  of  the  pow- 
der, and  of  the  floors  and  lining  of  the  magazine,  it  is 
of  the  greatest  importance  to  preserve  unobstructed  the 
circulation  of  the  air,  under  the  flooring  as  well  as  above. 
The  magazine  should  be  opened  and  aired  in  clear,  dry 
weather,  when  the  air  outside  is  colder  than  that  in- 
side the  magazine ;  the  ventilators  must  be  kept  free  ; 
no  shrubbery  or  trees  should  be  allowed  to  grow  so  near 
as  to  protect  the  building  from  the  sun.  The  moisture 
of  a  magazine  may  be  absorbed  by  chloride  of  calcium, 


EFFECTS    OF    GUNPOWDER.  35 

suspended  in  an  open  box  under  the  arch,  and  renewed 
from  time  to  time ;  quick-lime,  as  before  observed,  is 
dangerous. 

The  sentinel  or  guard  at  a  magazine,  when  it  is  open, 
should  have  no  fire-arms ;  and  every  one  who  enters  the 
magazine  should  take  off  his  shoes,  or  put  socks  over 
them;  no  sword  or  cane,  or  any  thing  which  might 
occasion  sparks,  should  be  carried  in. 

24.  Tran§p©rtation.  Barrels  of  powder  should  not 
be  rolled  for  transportation ;  they  should  be  carried  in 
hand-barrows,  or  slings  made  of  rope  or  leather.  In 
moving  powder  in  the  magazine,  a  cloth  or  carpet 
should  be  spread ;  all  implements  used  there  should 
be  of  wood  or  copper ;  and  the  barrels  should  never  be 
repaired  in  the  magazine. 

When  it  is  necessary  to  roll  the  powder,  for  its  bet- 
ter preservation  and  to  prevent  its  caking,  this  should 
be  done  with  a  small  quantity  at  a  time,  on  boards  in 
the  magazine  yard. 

In  wagons,  barrels  of  powder  must  be  packed  in 
straw,  secured  in  such  a  manner  as  not  to  rub  against 
each  other,  and  the  load  covered  with  thick  canvas. 


EFFECTS  OF  GUNPOWDER* 

25.  History,  etc.  The  projectile  arms  of  the  ancients, 
such  as  bows,  ballistas,  and  catapults,  were  operated 
by  the  same  motive  power — that  of  the  spring. 

Although  large  masses  were  thrown  from  these 
machines,  the  velocity  imparted  was  feeble,  as  the 
springs  rapidly  lost  their  power,  from  being  bent ;  and 

*  Vide  Piobert's  Cours  d? Artillerie. 


36  GUNPOWDEK. ITS    EFFECTS. 

the  introduction  of  gunpowder,  a  more  certain  as  well 
as  powerful  agent,  gradually  caused  them  to  be  super- 
seded. 

As  before  stated,  the  power  of  this  agent  is  essen- 
tially due  to  the  almost  instantaneous  development  of 
expansive  gases  and  heat  by  combustion ;  and  although 
its  properties  were  known  for  a  long  time,  its  use  was 
at  first  confined  to  fireworks  and  incendiary  composi- 
tions alone. 

The  advantage  of  using  an  agent  capable  of  commu- 
nicating great  velocity  to  a  projectile,  arises  not  only 
from  the  intensity  of  the  shock,  the  possibility  of  dis- 
abling a  large  number  of  men,  and  penetrating  very  re- 
sisting objects,  but  from  the  fact  that  it  allows  of  the 
use  of  lighter  machines,  whereby  the  projectile  can  be 
directed  with  greater  ease  and  certainty  against  its 
object. 

Although  the  combustible  nature  of  powder  was 
known  in  Asia  from  the  earliest  times,  and  its  prop- 
erties were  described  by  Marcus  Grsecus  and  Roger 
Bacon,  its  application  to  projectiles  seems  to  have  been 
a  subsequent  result  of  accident. 

It  is  stated  that  about  the  year  1330,  Berthold 
Schwartz,  a  monk  of  Fribourg,  was  engaged  in  making 
experiments  with  a  mixture  of  saltpetre,  sulphur,  and 
charcoal,  such  as  described  by  Marcus  Graecus,  and  had 
left  the  mixture  in  a  mortar,  covered  with  a  large  stone, 
when  it  unexpectedly  caught  fire  and  exploded,  throw- 
ing the  stone  to  a  distance  with  great  force.  The  ex- 
periment was  repeated,  and  with  such  success  that  mili- 
tary men  saw  at  once  that  it  could  be  applied  to  move 
large  projectiles.     Its  progress  as  a  projectile  power, 


DISCOVERY.  37 

however,  was  comparatively  slow,  and  it  was  only  at 
the  beginning  of  the  16th  century  that  it  was  generally 
used  for  military  purposes. 

For  a  long  time  after  its  introduction,  gunpowder 
was  used  in  the  form  of  dust,  or  "  mealed  powder," 
from  which  it  derived  its  name ;  but  it  was  found  dim- 
cult  to  load  small  arms  with  gunpowder  in  this  condi- 
tion, on  account  of  the  moisture  which  sometimes  collects 
in  the  bore  after  a  few  discharges.  To  overcome  this 
difficulty,  it  was  given  a  granular  form,  and  received  the 
name  of  "  musket  powder."  It  was  soon  discovered, 
however,  that  two  parts  of  grained  powder  produced  as 
much  effect  as  three  parts  of  mealed  powder ;  but  the 
larger  fire-arms  of  the  day  had  not  sufficient  strength  to 
resist  this  increased  force,  and  mealed  powder  continued 
to  be  used  until  the  close  of  the  16th  century. 

At  first,  the  ingredients  of  powder  were  converted 
into  cake  with  a  hand-pestle;  a  process  which  gave 
grains  of  very  irregular  size  and  shape.  It  was  after- 
ward discovered  that  the  quality  could  be  much  im- 
proved by  careful  manipulation,  without  sensibly  alter- 
ing the  proportions  of  the  ingredients  first  established. 

Any  improvement  in  gunpowder  which  increases  its 
strength,  also  increases  its  injurious  effects  on  the  arms 
in  which  it  is  used.  It  becomes  necessary,  therefore,  to 
study  the  form  and  thickness  of  fire-arms,  and  the  na- 
ture of  the  agent  whose  operations  they  are  intended  to 
restrain  and  direct. 

It  is  impossible  to  embrace  in  a  single  glance  the  de- 
tails of  a  phenomenon  as  complicated  as  the  explosion 
of  a  charge  of  powder.  The  senses  cannot  detect  the 
relations  which  exist  between  the  partial  operations  of 


38  GUNPOWDER. ITS    EFFECTS. 

a  phenomenon,  where  they  are  produced  with  such  ra- 
pidity that  they  seem  blended  into  one.  In  this  case 
the  only  sure  method  of  investigation  is  to  separately 
study  the  different  facts,  and  then  unite  them  as  a  whole, 
borrowing  from  the  physical  sciences  a  thorough  knowl- 
edge of  the  substances   operated  upon. 

If  the  numerous  circumstances  which  influence  the 
results  of  the  explosion  of  gunpowder,  and  the  enor- 
mous expansive  force  which  is  developed  in  its  limited 
duration,  prevent  us  from  accurately  determining  the 
measure  of  its  effects,  we  can  at  least  determine  the 
limits  between  which  this  measure  is  included ;  which 
is  sufficient  for  artillery  purposes.  From  the  results 
thus  obtained  were  calculated  the  iron  and  bronze  how- 
itzers introduced  to  supersede  those  of  Gribeauval's  sys- 
tem. With  less  thickness  of  metal,  these  pieces  were 
found  to  answer  every  requirement  of  service ;  a  fact 
which  tends  to  confirm  the  accuracy  of  the  data  from 
which  they  were  constructed. 

26.  Expio§i©n.  The  phenomenon  of  the  explosion 
of  powder  may  be  divided  into  three  distinct  parts,  viz.  : 
ignition,  inflammation,  and  combustion. 

By  ignition  is  understood  the  setting  on  fire  of  a 
particular  point  of  the  charge;  by  inflammation,  the 
spread  of  the  ignition  from  one  grain  to  another ;  and 
by  combustion,  the  burning  of  each  grain  from  its  sur- 
face to  centre. 

27.  ignition.  Gunpowder  may  be  ignited  by  the 
electric  spark,  by  contact  with  an  ignited  body,  or  by  a 
sudden  heat  of  572°  Fahrenheit.  A  gradual  heat  de- 
composes powder  without  explosion  by  subliming  the 
sulphur.      Flame  will  not  ignite  gunpowder  unless  it 


COMBUSTION.  39 

remains  long  enough  in  contact  with  the  grains  to  heat 
them  to  redness.  Thus,  the  blaze  from  burning  paper 
may  be  touched  to  grains  of  powder  without  igniting 
them,  owing  to  the  slight  density  of  the  name,  and  the 
cooling  effect  of  the  grains.  It  may  be  ignited  by  fric- 
tion, or  a  shock  between  two  solid  bodies,  even  when 
these  are  not  very  hard.  Experiments  in  France,  in 
1825,  show  that  powder  may  be  ignited  by  the  shock 
of  copper  against  copper,  copper  against  iron,  lead 
against  lead,  and  even  lead  against  wood ;  in  handling 
gunpowder,  therefore,  violent  shocks  between  all  solid 
bodies  should  be  avoided. 

The  time  necessary  for  the  ignition  of  powder  varies 
according  to  circumstances.  For  instance,  damp  pow- 
der requires  a  longer  time  for  ignition  than  powder  per- 
fectly dry,  owing  to  the  loss  of  heat  consequent  on  the 
evaporation  of  the  water ;  a  powder,  the  grain  of  which 
has  an  angular  shape  and  rough  surface,  will  be  more 
easily  ignited  than  one  of  rounded  shape  and  smooth 
surface  ;  a  light  powder,  more  easily  than  a  dense  one ; 
and  a  powder  made  of  a  black  charcoal,  more  easily  than 
one  made  of  red,  inasmuch  as  the  latter  is  compelled 
to  give  up  its  volatile  ingredients  before  it  is  acted  on 
by  the  nitre. 

28.  Combu§tion.  The  velocity  of  combustion  is  the 
space  passed  over  by  the  surface  of  combustion  in  a 
second  of  time,  measured  in  a  direction  perpendicular 
to  this  surface. 

The  diameter  of  the  largest-size  grain  of  cannon- 
powder  does  not  exceed  0.1  inch ;  the  time  of  its  com- 
bustion, therefore,  is  altogether  too  transient  to  be 
ascertained  by  direct  observation.     It  may  be  deter- 


40  GUNPOWDER. ITS    EFFECTS. 

mined  by  compressing  the  composition 
into  a  tube  and  burning  it,  or  by  burn- 
ing the  "  press-cake."  In  the  latter  case, 
take  a  prism  of  the  cake  about  fourteen 
inches  long  and  one  inch  square  at  the 
base.  Smear  the  sides  with  hogs'  lard, 
and  place  it  on  end  in  a  shallow  dish  of 
water.  The  object  of  the  lard  is  to  pre- 
vent the  spread  of  the  flame  to  the  sides ; 
and  the  water  is  to  prevent  the  lower  end  from  being 
ignited  by  burning  drops  of  powder.  Set  the  upper 
end  on  fire,  and  note  the  time  of  burning  of  the  column 
with  a  stop-watch  beating  tenths  of  seconds. 

In  either  way  it  will  be  shown  that  the  composition, 
if  homogeneous,  burns  in  parallel  layers,  and  that  the 
velocity  of  combustion  is  uninfluenced  by  the  size  of 
the  column,  or  by  the  temperature  and  pressure  of  the 
surrounding  gas. 

The  velocity  of  combustion  of  dry  French  war- 
powder  is  thus  found  to  be  0.48  in.,  and  of  English 
powder,  which  American  powder  closely  resembles,  it 
is  about  0.4  in. 

It  may  be  shown  by  direct  experiment  that  the 
burning  of  a  grain  of  powder  in  a  fire-arm,  is  progres- 
sive, and  that  the  size  of  the  grain  exerts  a  great  influ- 
ence on  the  velocity  of  the  projectile,  especially  in  short 
arms. 

For  this  purpose  take  a  mortar  eprouvette  and  load 
it  with  a  single  fragment  of  powder  weighing  forty-six 
grains ;  fire  it,  and  the  ball  will  not  be  thrown  out  of 
the  bore ;  divide  the  same  weight  into  seven  or  eight 
fragments,  and  it  will  barely  be  thrown  out  of  the 


COMBUSTION.  41 

bore ;  divide  it  into  fifteen  fragments,  and  it  will  "be 
thrown  about  ten  feet;  fifty  fragments  will  throw  it 
about  thirty  feet ;  and  the  same  weight  of  cannon-pow- 
der, about  one  hundred  and  seventy  feet. 

The  progressive  burning  of  powder  is  further  con- 
firmed by  the  fact,  that  burning  grains  are  sometimes 
projected  from  a  gun  with  sufficient  force  to  perforate 
screens  of  paper,  wood,  and  lead,  at  considerable  dis- 
tances. It  is  even  found  that  they  are  set  on  fire  in  the 
gun,  and  afterward  extinguished  in  the  air  before  they 
are  completely  consumed.  The  large  grains  of  powder 
used  in  the  fifteen-inch  columbiad  are  thrown  out  burn- 
ing, to  a  distance  of  one  hundred  yards. 

The  velocity  of  combustion  of  powder  varies  with 
the  nature,  proportions,  trituration,  density,  and  condi- 
tion of  the  ingredients. 

Purity  of  ingredients.  To  secure  the  greatest  ve- 
locity of  combustion,  it  is  necessary  that  the  nitre  and 
sulphur  should  be  pure,  or  nearly  so.  This  can  always 
be  effected  by  a  proper  attention  to  the  prescribed 
modes  of  refining ;  but  with  the  charcoal  it  is  different, 
for  the  part  which  it  plays  in  combustion  depends  upon 
certain  characters  which  are  indicated  by  its  color  and 
texture.  The  velocity  of  combustion  will  be  greater 
for  red  charcoals  than  those  that  are  black  and  strongly 
calcined  ;  and  for  light  and  friable  charcoals,  than  those 
that  are  hard  and  compact.  It  appears,  in  fact,  to  be 
nearly  proportioned  to  t.-e  combustibility  of  the  char- 
coals given  in  the  tables  on  page  19. 

Proportions.  The  proportions  of  the  ingredients 
have  a  very  great  effect  on  the  combustion ;  by  vary- 
ing them,  all  velocities  between  0  and  .55  inch  can  be 


42 


GUNPOWDER. ITS    EFFECTS. 


obtained ;  the  latter  number  can  scarcely  be  exceeded. 
The  proportions  which  give  a  maximum,  appear  to  be 
comprised  between  the  two  following: 

Nitre,  76.  Charcoal,  15.  Sulphur,  9. 

"      76.  "  14.  "       10. 

As  it  is  often  useful  in  preparing  fireworks  to  know 
the  proportions  which  will  give  a  certain  velocity  of 
combustion,  a  table  is  given  of  a  series  of  proportions 
of  nitre,  sulphur,  and  charcoal,  and  the  corresponding 
velocities  of  combustion : 

Sixty  parts  of  nitre,  compounded  with  certain  pro- 
portions of  sulphur  and  charcoal,  gave  the  following 
velocities: 


Parts  of 
Sulphur. 

Parts  of  Black  Charcoal. 

0 

5 

10 

11 

15 

20 

30 

60 

Inch. 

Inch. 

Inch. 

Inch. 

Inch. 

Inch. 

Inch. 

Inch. 

0 

.0 

.02 

.  11 

.14 

.24 

.34 

.43 

.07 

5 

.0 

.05 

.24 

.30 

.43 

.47 

.  35 

.00 

8 

.  0 

.06 

.50 

.51 

.49 

.41 

.20 

.00 

15 

.0 

.08 

.47 

.49 

.47 

.39 

.  16 

.00 

.0 

.  11 

.43 

.44 

.36 

.35 

.  14 

.00 

20 

.0 

.16 

.39 

.40 

.  38 

.30 

.  10 

.00 

30 

60 

.0 

.27 

.34 

.33 

.29 

.  21 

.01 

.00 

.0 

.00 

00 

.00 

.00 

.  00 

.00 

.oo     ! 

1 

It  will  be  seen  that  the  proportions  6 — 1 — 1  are 
among  those  that  give  the  greatest  amount  of  gas  in  a 
given  time,  other  circumstances  being  equal;  for  the 


TRITURATION. 


43 


reason,  that  the  weight  burned  during  this  time  is 
greater,  and  because  each  unit  of  weight  gives  a  greater 
volume  of  gas. 

Trituration.  Trituration  of  the  ingredients  increases 
the  velocity  of  combustion ;  and  this  increase  is  much 
greater  as  the  proportions  approach  those  which  give 
the  greatest  velocity.  For  the  results  of  experiments  on 
this  point,  see  accompanying  table : 


11 

Velocity  of  combustion. 

Remarks. 

Composition. 

A. 

B. 

c. 

Hours. 

0 

1 

2 
3 
4 
5 
10 

Inches. 

.12 
.31 
.38 
.40 

.44 
.46 

.48 

Inches. 

Inches. 

.13 

.25 
.29 
.32 
.34 
.35 
.37 

.0189 
.0192 
.0200 
.0204 
.0212 
.0216 
.0236 

Compositions  dry. 

Nitre-.    Ch'coal.  Sulphur.       Composition. 

A,  75.00   12.5    12.50  Gunpowder. 

B,  68.00    12.0    28.00  Fuze  composition. 

C,  66.66      2.0    31.34  Port-fire      " 

The  nitre  was  taken  as  it  came  from 
the  refinery.     The  sulphur  and  charcoal 
had  already  been  triturated  in  the  roll- 
ing-barrels. 

Density.  For  each  set  of  proportions,  the  maximum 
velocity  corresponds  to  a  very  small  density.  By  in- 
creasing the  density,  the  velocity  is  diminished;  and 
more  rapidly  for  quick  compositions  than  slow  ones. 
When  in  the  form  of  a  dust,  gunpowder  composition 
burns  more  slowly  without  compression  than  with  it. 
For  the  results  of  experiments  on  the  preceding  compo- 
sitions, see  the  following  table ;  the  trituration  was  ex- 
tended to  ten  hours : 


44 


GUNPOWDER. ITS    EFFECTS. 


Density. 

Velocity  of  combustion. 

Remarks. 

Composition. 

A. 

B. 

C. 

0.80 

.360 

.310 

The  pulverized  composition  is  simply 
poured  into  a  tube,  and  settled  by 
striking  lightly  on  a  table. 

1.00 

.440 

.410 

.0319 

The  composition  poured  in  as  above, 
and  compressed  under  a  weight  of 
22  lbs.  without  shock. 

1.20 

.470 

.390 

.0295 

Composition  driven  with  a  mallet 
weighing  2.2  lbs.,  falling  through  a 
height  of  3.9  inches. 

1.40 

.480 

.380 

.0252 

Same,  save  the  height,  which  was   27 

inches. 
These  densities  were  obtained  by   in- 

1.60 

.890 

.366 

.0224 

creasing  the  number  of  blows  with 

1.80 

.443 

.360 

.0220 

the  mallet  for  each  ladleful  of  compo- 
sition. 

2.00 

.340 

The  density  of  a  composition  under  the 

2.16 

.330 

same  pressure,  increases  with  the 
trituration  of  the  ingredients. 

Moisture.  By  moistening  the  composition  with  pure 
water,  alcohol,  or  vinegar,  and  then  drying  it  com- 
pletely, the  velocity  of  combustion  is  increased.  With 
pure  water  alone,  this  increase  of  velocity  may  amount 
to  0.1  of  an  inch.  On  the  contrary,  the  velocity  is 
diminished  where  oils,  fatty  or  resinous  substances,  are 
added  to  the  composition,  or  when  it  incloses  water  or 


other  liquids. 


OW' 


'-v  &4  * 


d>.^ 


Dry  Powder,  or  one  containing  \  per  cent,  of  moisture,  has  a  velocity  of  0.48  in. 


„ 


0.39  in. 
0.33  in. 


29.  Law  of  formation  of  gaseous  product*.  When 
the  form  and  size  of  the  grains  and  the  velocity  of  com- 
bustion are  known,  we  can  ascertain,  at  any  given  mo- 


FOKMATION  OF  GASEOUS  PRODUCTS. 


45 


Fig.  2. 


ment,  the  amount  of  powder  consumed,  as  the  velocity 
is  uniform  and  independent  of  the  surface. 

Spherical  grain.  Take  a  spherical  grain  of  powder 
of  homogeneous  structure,  one  that  will  completely  burn 
up  in  -Jq-  of  a  second.  Apply  fire  at  any  point 
of  its  surface,  the  flame  will  immediately 
envelop  it,  and  burn  away  the  first  spheri- 
cal layer ;  if,  for  example,  we  suppose  the 
time  of  this  partial  combustion  be  TV  of 
the  time  required  to  burn  up  the  entire  grain,  then  the 
radius  of  the  remaining  sphere  will  be  only  T9^-  of  the 
first ;  but  the  volumes  of  spheres  being  to  each  other 
as  the  cubes  of  their  radii,  the  primitive  sphere  will  be 
to  the  one  which  remains  after  the  burning  of  the  first 
layer,  as  1.0  is  to  0.729,  the  cube  of  .9.  Subtracting  the 
second  of  these  numbers  from  the  first,  we  shall  have 
0.271,  which  expresses  the  difference  of  volumes  of  the 
two  spheres,  or  the  amount  consumed  in  the  first  TV  of 
time,  compared  to  that  of  the  entire  grain.  By  making 
similar  calculations  on  the  other  layers,  we  shall  obtain 
the  results  contained  in  the  following  table : 


Time  of  burning 

0.000 

.100 

.200 

.300 

.400 

.500 

.600 

.700 

.800 

.900 

1.000 

Decreasing  radii 

1.000 

.900 

.800 

.700 

.600 

.500 

.400 

.300 

.200 

.100 

0.000 

Volumes  of  grain 

1.000 

.729 

•m 

.343 

.216 

.125 

.064 

.027 

.008 

.001 

0.000 

Volumes  burnt 

0.000 

.271 

.488 

.657 

.784 

.875 

.936 

.973 

.992 

.999 

1.000 

Volumes  burnt  in  each  0".10 

0.000 

.271 

.217 

.171 

.127 

.091 

.061 

.037 

.019 

.007 

0.001 

It  will  be  seen  from  this,  that  for  equal  intervals  of 
time,  those  taken  in  the  first  period  of  combustion  give 
forth  very  much  larger  amounts  of  gas  than  those  taken 
in  the  last.     If,  instead  of  a  sphere,  we  suppose  the 


46  GUNPOWDER. ITS    EFFECTS. 

grain  to  be  &  polyhedron  circumscribing  a 

sphere,  the  burning  layers  being  parallel, 

the  decreasing  grain  will  continue  to  be 

a  similar  polyhedron,    circumscribing   a 

sphere.     The  results  given  in  the  table 

will  be  strictly  true  for  this  case,  as  well  as  for  grains 

of  conical  or  cylindrical  form,  provided  their  bases  be 

equal  to  their  heights. 

General  formula.  A  general  formula  may  be  de- 
duced to  show  the  amount  of  gas  developed  at  any 
instant  of  the  combustion  of  a  grain  or  charge  of  pow- 
der. For  this  purpose  take  a  spherical  grain  of  powder, 
and  consider  it  inflamed  over  its  entire  surface. 

Let  t  represent  the  time  of  burning,  from  the  in- 
stant of  ignition  to  the  moment  under  consideration:  t', 
the  time  necessary  to  burn  from  the  surface  to  the  cen- 
tre, or  total  combustion:  i?,  the  radius  of  the  grain. 

Since  the  combustion  passes  over  the  radius  JR  in 

the  time  t',  the  velocity  of  combustion  is  equal  -7",  and 

for  the  time  t7  it  will  pass  over  the  space  t— -  or  H—  ; 

t  t 

the  radius  of  the  decreasing  sphere  will  therefore  be 
jg/l—  —  )       The    volume    of  the    grain   of   powder 

and   that   of    the    decreasing   sphere    are   -^nfi8    and 

o 


A.  /  t  \3 

7r-nIPll—  —  )>  respectively;    and   their  difference,  or 
the    quantity   of    powder   burned,   will   be   equal   to 


3 


GENERAL    FORMULA.  47 

The  first  factor  of  this  expression  represents  the 
primitive  volume  of  a  grain  of  powder,  and  the  other 
expresses  the  relation  of  the  volume  burned  to  the 
primitive  volume. 

The  same  expression  will  answer  for  all  the  grains 
of  a  charge  of  powder,  if  they  are  of  the  same  size  and 
composition ;  consequently,  if  we  let  A  represent  the 
volume  or  weight  of  the  grains  composing  a  charge  of 
powder,  the  quantity  remaining  unburned  after  the  time 

t  will  be  represented  by  Ay  1 -t  );  and  the   quantity 

burned,  by  A  (\-(l  -J  J). 

Although  the  grains  of  powder  are  not  spherical, 
their  sharp  angles  are  partially  worn  away  by  rubbing 
against  each  other  in  glazing  and  in  transportation;  and 
the  mode  of  fabrication  and  inspection  reduces  the 
variation  in  size  within  narrow  limits;  therefore,  if 
we  examine  the  influence  which  the  actual  form  and 
size  of  the  grains  exercises  over  the  phenomenon  of 
combustion  of  powder,  we  shall  find  that  the  effect 
varies  but  slightly  from  that  due  to  the  spherical  form. 

Application  to  ordinary  powder.  Take  a  grain  of  ob- 
long form,  like  that  of  a  spheroid,  or  cylinder  termi- 
nated by  two  hemispheres:  it  will  present  a  greater 
surface  than  a  spherical  grain  of  the  same  weight,  and 
consequently  the  amount  of  gas  formed  from  it  in  the 
first  instants  of  time,  will  be  greater,  and  the  duration 
of  the  combustion  will  lie  less.  It  can  be  shown,  how- 
ever, that  so  long  as  the  size  of  the  grains  is  kept  with- 
in the  regulation  limits,  this  influence  will  be  slight. 
To  do  this,  take  an  oblong  grain  the  cylindrical  part  of 


48 


GUNPOWDEK. ITS    EFFECTS. 


which  has  a  diameter  of  .054  in.,  let  it  be  terminated 
by  two  hemispheres,  and  have  a  total  length  of  .097 
in.  (these  being  the  minimum  and  maximum  size  of 
a  grain  of  French  cannon-powder,  respectively) ;  its 
weight  will  be  about  .07  grain,  or  yy?  of  a  gramme, 
and  with  a  velocity  of  combustion  of  0.48  it  will  take 
0.056"  to  burn  up  completely. 

French  war-powder  is  composed  of  grains  of  different 
weights,  numbering  about  310  to  every  gramme,  or  15.4 
grs.  Troy.  If,  therefore,  powder  contain  oblong  grains 
of  the  size  stated  above,  there  must  be  others  still 
smaller :  if  we  suppose  them  to  be  in  equal  quantities, 
and  the  larger  to  be  ¥ fy  of  the  unit  of  weight,  then  the 
smaller  must  be  equal  to  T|¥  of  the  unit  of  weight ; 
which  would  be  equal  to  spheres  with  a  radius  of  0.027 
inch.  Comparing  the  quantities  of  gas  developed  in 
intervals  of  .008",  or  about  |  of  the  time  necessary  for 
the  combustion  of  the  smallest  grains,  we  obtain  the 
result  in  the  following  table  : — 


Relation  of  the  volume  of  powder  burned,  to  the  vol- 

Kinds of  grains  of  Powder. 

ume  of  the  grains  after  a  time  of 

0".008 

0".016 

0".024 

0".032 

0".040 

0".048 

0".056 

Elongated  grains,  diamr.  .054  in. ; 

length,    0.98   in.,— 210    to  the 

gramme,  or  15.4  grs., 

0.310 

0.555 

0.737 

0.864 

0.946 

0.987 

1.000 

Spherical    grains    ol    410  to  the 

gramme,  or  .056  in.  diameter, 

0.357 

0.616 

0.794 

0.907 

0.968 

0.994 

0.999 

Elongated  and  spherical  grains  as 

above,  in  equal  quantities,  form- 

ing a   mixture  of    310  to  the 

gramme, 

0.333 

0.585 

0.766 

0.885 

0.958 

0.990 

0.999 

Spherical   grains   of  310    to   the 

gramme,  or  0.063  in.  diameter, 

0.330 

0.580 

0.758 

0.875 

0.948 

0.985 

0.998 

Difference  between  mixed  grains 

and  spherical  grains  of  the  same 

mean  weight, 

0.003 

0.005 

0.008 

0.010 

0.010 

0.005 

0.001 

The  differences  in  the  results  do  not  much  exceed  T±T, 


INFLAMMATION.  49 

and  may  be  neglected  in  practice  ;  we  may  accordingly 
consider  all  the  grains  of  a  charge  of  powder  as  spheres 
with  radii  corresponding  to  their  mean  weight.  This 
mean  weight  is  an  important  element,  and  may  be  de- 
termined by  counting  the  number  of  grains  in  a  given 
charge,  and  dividing  the  weight  of  the  charge  by  this 
number. 

In  war-powder  the  largest  portion  of  each  grain  is 
burned  in  the  first  two-tenths  of  the  time  required  to 
consume  the  entire  grain  :  as  it  has  been  shown  that  a 
grain  of  ordinary  cannon-powder  requires  0.1  second 
for  its  combustion,  the  largest  portion  of  the  grain  will 
be  burned  in  the  first  T| -^  of  a  second.  If  we  consider 
the  velocity  of  the  projectile  on  leaving  a  gun,  and  the 
time  necessary  to  overcome  its  inertia  in  the  first  period 
of  its  movement,  we  shall  see  that  a  very  large  portion 
of  each  grain  is  burned  up  before  the  projectile  leaves 
the  gun.  If  the  size  of  the  grain  be  increased,  the 
effect  will  be  to  diminish  the  amount  of  gas  evolved  in 
the  first  instants  of  time,  and  to  diminish  the  pressure 
on  the  breech*  This  principle  has  been  made  use  of 
lately  to  increase  the  endurance  of  large  cannon. 

29.  inflammation.  When  grains  of  powder  are  uni- 
ted to  form  a  charge,,  and  fire  is  communicated  to  one 
of  them,  the  heated  and  expansive  gases  evolved,  insin- 
uate themselves  into  the  interstices  of  the  charge,  en- 
velop the  grains  and  ignite  them,  one  after  the  other. 

*  This  idea  has  been  carried  out  more  fully  in  the  experiments  of  Captain  Rodman, 
by  converting  the  powder  into  one  or  more  cakes,  which  are  perforated  with  numer- 
ous small  holes  for  the  passage  of  the  flame.  In  this  way  a  large  portion  of  the 
powder  is  consumed  on  an  increasing  instead  of  a  decreasing  surface,  and  the 
amount  of  gas  given  out  in  the  last  moments  will  be  greater  than  in  the  first ;  and 
thus  the  strain  on  the  breech  of  a  gun  may  be  very  much  diminished  without  pro- 
portionately diminishing  the  velocity  communicated  to  the  projectile.  For  actual 
results  obtained  with  this  kind  of  powder,  see  Note  appended  to  section  109. 
4 


50  GUNPOWDER. ITS    EFFECTS. 

This  propagation  of  ignition  is  called  inflammation, 
and  its  velocity  the  velocity  of  inflammation.  It  is 
much  greater  than  that  of  combustion,  and  it  should  not 
be  confounded  with  it. 

The  velocity  with  which  inflamed  gases  move  in  a 
resisting  tube,  like  a  cannon,  is  very  great.  Hutton  cal- 
culated it  to  be  from  3,000  to  5,000  feet  per  second ;  and 
Robins  determined  it  by  experiment  to  be  about  7,000 
feet  per  second. 

But  when  these  gases  are  forced  to  pass  through  the 
interstices  of  powder,  the  resistance  offered  will  consider- 
ably diminish  the  velocity  of  their  expansion  :  it  is  found 
to  vary  with  the  form  and  size  of  the  grains ;  and  may 
be  supposed  to  be  reduced  to  33  feet  per  second.  The 
velocity  of  combustion,  as  before  stated,  is  only  .48  inch 
per  second. 

Although  the  velocity  of  inflammation  of  a  train  of 
powder  can  afford  but  an  imperfect  idea  of  this  velocity 
in  a  gun,  it  may  be  interesting  to  study  it. 

The  velocity  of  inflammation  of  a  train  of  powder 
generally  varies  with  the  size  of  the  grains,  with  the 
quantity  of  powder  employed,  and  the  disposition  of  the 
surrounding  bodies,  as  will  be  shown  by  the  following 
results  of  actual  experiment. 

The  amount  of  powder  in  each  train  was  about 
.11  lb.  to  the  linear  foot,  and  the  time  corresponding  to 
the  distances  was  one  second. 

On  a  plane  surface  in  the  open  air,      .  7.87  feet. 

In  an  uncovered  trough,           .         .  .    8.13    " 

In  a  linen  tube,            ....  11.38    « 

In  the  same  tube  placed  in  the  trough,  17.48    " 

In  the  trough  covered  up,          .  27.88    " 


INFLAMMATION.  51 

These  velocities  are  less  than  those  obtained  in  fire- 
arms, for  the  reason  that  the  powder  is  not  only  confined 
at  the  sides,  but  at  one  end,  which  was  not  the  case  in 
the  experiment  with  the  covered  trough,  where  it  could 
expand  in  both  directions. 

A  velocity  of  more  than  three  hundred  feet  can  be 
obtained  by  burning  quick-match  inclosed  in  a  cloth 
tube. 

The  size  of  the  cross-section  influences  the  velocity, 
as  was  shown  by  burning  a  train  containing  .062  lb.  per 
foot  in  an  open  trough :  the  velocity  was  5.77  feet,  in- 
stead of  7.87  feet;  and  in  a  covered  trough  it  was 
twenty  feet,  instead  of  27.88.  The  velocity,  therefore, 
increases  with  the  cross-section  of  the  train. 

To  determine  the  influence  of  the  size  of  the  grains 
on  the  velocity  of  inflammation,  two  trains  were  fired, 
one,  composed  of  fine  grains,  and  the  other  of  large 
ones ;  the  velocity  of  the  first  was  8.2  feet,  and  the 
second  was  7.54.  This  difference  was  due  to  the  greater 
amount  of  gas  developed  by  the  small  grains  in  the  first 
instants  of  combustion. 

The  nature  of  the  charcoal  exerts  an  influence,  the 
black  being  more  favorable  to  inflammation  than  the 
red. 

For  a  specific  gravity  of  1.3,  the  velocity  is  7.5  feet. 

«  u  "16         u  "79    u 

Light  powder  is  therefore  found  to  be  more,  inflam- 
mable than  heavy. 

If  the  grains  be  round  the  interstices  are  larger,  and 
more  favorable  to  the  passage  of  the  flame,  and  the  in- 


52  GUNPOWDER. PEODTTCTS    OF    COMBUSTION. 

flanimation  of  the  mass.  If  they  be  sharp  and  angu- 
lar, they  will  close  npon  each  other  in  such  a  way  as  to 
reduce  the  interstices;  and  although  the  ignition  of 
such  grains  may  be  more  rapid,  its  propagation  will  be 
diminished. 

It  has  been  shown  that,  when  powder  is  burned  in 
an  open  train,  fine  powder  inflames  more  rapidly  than 
coarse ;  such,  however,  is  not  the  case  in  fire-arms,  owing 
to  the  diminution  of  the  interstices.  If  a  charge  were 
composed  of  mealed  powder,  the  flame  could  no  longer 
find  its  way  through  interstices,  and  the  velocity  of  in- 
flammation and  combustion  would  become  the  same. 
The  velocity  of  inflammation  of  powder  compressed  by 
pounding  is  about  .64  inch,  while  that  of  mealed  pow- 
der in  the  same  condition  is  only  .45  in. 

PRODUCTS,  ETC.,  OF  COMBUSTION. 

30.  Nature  of  products  Temperature  and  atmos- 
pheric pressure  considerably  influence  the  products  ob- 
tained from  burning  gunpowder.  When  exposed  in  the 
open  air  to  a  temperature  gradually  increasing  to  572° 
Fahrenheit,  the  sulphur  sublimes,  taking  with  it  a  por- 

Note. — By  compressing  grain-powder  under  a  hydrostatic  press  it  may  be  con- 
verted into  a  solid  cake,  and  be  used  in  loading  fire-arms,  in  place  of  the  ordinary 
cartridge.  No  cement  is  required  to  unite  the  grains,  as  the  pressure  brings  the 
particles  of  the  surface  of  the  grains  within  the  limits  of  cohesive  attraction,  in 
the  same  way  that  artificial  limestone  is  formed  by  compressing  sand.  As  the 
pressure  diminishes  the  interstices  of  the  grains,  it  also  diminishes  the  velocity  of 
inflammation,  aad  the  rapidity  with  which  the  charge  is  converted  into  flame. 

Experiments  made  at  "West  Point,  on  some  specimens  of  powder  thus  prepared 
by  Dr.  Doremus,  of  New  York,  showed  that  the  pressure  on  the  surface  of  the 
bore  may  be  increased  or  diminished  by  diminishing  or  increasing  the  pressure  on 
the  cakes. 

The  cakes  were  covered  by  a  water-proof,  but  highly  inflammable  varnish, 
which  protected  the  powder  from  moisture,  without  apparently  diminishing  its 
inflammability. 


NATURE    OF   PEODUCTS.  53 

tion  of  the  carbpn.  This  was  shown  by  Saluces,  who 
passed  the  volatilized  products  through  a  screen  of  very 
fine  cloth,  and  found  carbon  deposited  on  it.  Powder 
may  be,  therefore,  completely  decomposed  by  a  gradual 
heat,  without  explosion;  but  when  suddenly  brought 
in  contact  with  an  ignited  body,  the  temperature  of 
which  is  at  least  572°  Fahrenheit,  the  sulphur  has  not 
time  to  sublime  before  explosion  takes  place 

The  proportions  for  war-powder  for  the  United 
States  service  are  seventy-six  parts  of  nitre,  ten  of 
sulphur,  and  fourteen  of  carbon.  By  the  atomic  theory 
the  proportions  should  be  74.64  nitre,  11.85  sulphur, 
13.51  carbon.  If  we  adopt  these  last  proportions,  the 
formula  for  gunpowder  becomes 

(jvo5+xo)+s+sa 

If  we  suppose  the  ingredients  to  be  pure,  and  to  arrange 
themselves  under  the  influence  of  heat  according  to 
their  strongest  affinities,  there  will  result  one  equivalent 
of  nitrogen,  three  of  carbonic  acid,  and  one  of  sulphide 
of  potassium,  for 

(JY05+1T0)+S+ZC=JV+3C02+SK 
The  products  are,  therefore,  solid  and  gaseous.  Usually, 
powder  contains  a  slight  quantity  of  moisture ;  the  in- 
gredients are  not  absolutely  pure,  nor  are  they  propor- 
tioned strictly  according  to  their  combining  equivalents ; 
it  might  be  expected,  therefore,  that  the  actual  would 
differ  from  the  theoretical  results. 

The  actual  gaseous  products  obtained  by  combustion 
are,  principally  nitrogen  and  carbonic  acid,  sometimes 
carbonic  oxide,  a  little  sulphuretted  hydrogen,  carburetted 
hydrogen,  and  nitrous  oxide.  The  solid  products  are, 
sulphide  of  potassium,  sulphate  of  potassa,  sub-carbonate 


54  GUNPOWDER. PRODUCTS    OF    COMBUSTION. 

of  potassa  (mingled  with  a  little  carbon),  and  traces  of 
sulphur. 

When  the  sulphide  of  potassium  comes  in  contact 
with  the  air,  it  is  converted  into  sulphate  of  potassa, 
and  gives  rise  to  the  white  smoke  which  follows  the  ex- 
plosion of  gunpowder.  A  portion  of  the  sulphide  is 
sometimes  condensed  on  the  surface  of  the  projectile, 
which  accounts  for  the  red  appearance  of  shells,  some- 
times observed  in  mortar-firing. 

The  solid  products  are  probably  volatilized  at  the 
moment  of  explosion  by  the  high  temperature  which 
accompanies  the  combustion ;  but,  coming  in  contact 
with  bodies  of  much  lower  temperature,  they  are  imme- 
diately condensed.  In  chambered  arms,  small  drops  of 
sulphur  may  be  observed  condensed  on  the  sides  of  the 
bore,  which  show  that  the  sulphur  has  been  volatilized ; 
and  we  know  that  good  powder  burns  on  paper  and 
leaves  no  trace.  This  fact,  however,  was  most  com- 
pletely shown  by  the  experiments  of  Count  Rumford. 
This  celebrated  observer  used  a  small  eprouvette  of 
great  strength,  which  he  partially  filled  with  powder, 
and  hermetically  closed  with  a  heavy  weight.  The 
powder  was  fired  by  heating  a  portion  of  the  eprouvette 
to  redness.  Whenever  the  force  was  sufficient  to  raise 
the  weight,  the  entire  products  escaped;  when  it  was 
not,  a  solid  substance  was  found  condensed  on  the  sur- 
face of  the  bore  furthest  from  the  source  of  heat. 

31.  Temperature.  The  temperature  of  the  gaseous 
products  of  fired  gunpowder  has  been  variously  estima- 
ted. Saluces  determined  by  experiment  that  pure  cop- 
per, which  melts  at  a  temperature  of  4,622  Fahr.,  was 
not  always  melted  by  them ;   while  brass,  the  melting- 


DETERMINATION    OF    FORCE. 


55 


point  of  which  is  about  3,900  Fahr.,  was  invariably 
melted  ;  he  was,  therefore,  induced  to  place  their  tem- 
perature at  about  4,300  Fahr.  As  metals  absorb  a  large 
amount  of  heat  before  melting,  it  is  probable  that  the 
temperature  of  fired  gunpowder  is  actually  more  than 
is  here  stated. 


DETERMINATION  OF  THE  FORCE   OF 
GUNPOWDER. 

32.  Absolute  force.  The  absolute  force  of  gunpow- 
der is  measured  by  the  pressure  which  it  exerts  when 
it  exactly  fills  the  space  in  which  it  is  fired.  Various 
experiments  have  been  made  to  determine  mechanically 
the  absolute  expansive  force  of  fired  gunpowder,  but 
with  widely  different  results.  Robins  estimated  it  at 
1,000  atmospheres,  Hutton  at  1,800,  D'Antoni  from  1,400 
to  1,900,  and  Rumford  carried  it  as  high  as  100,000 
atmospheres.*  These  discrepancies  arise,  in  a  great 
measure,  from  the  very  great  difference  which  exists  be- 
tween the  expansive  force  of 
the  gases  in  the  different  mo- 
ments of  combustion,  and  from 
a  want  of  coincidence  in  the 
observations. 

The  apparatus  used  by 
Rumford  to  determine  this 
point  consisted,  essentially,  of 
a  small  eprouvette,  E,  capa- 
ble of  holding  exactly  25 
grains  of  powder.     The  orifice 


*  RodmaiVs  experiments  show  the  absolute  pressure  to  be  at  least  13,333  atmos- 
pheres, or  200,000  lbs.  to  the  square  inch. 


56  GUNPOWDER. FORCE. 

was  closed  with  a  heavy  weight,  and  the  powder  was 
fired  by  heating  the  stem  of  the  eprouvette,  S,  with  a 
redhot  cannon-ball,  B.  For  the  first  trial,  he  filled  the 
eprouvette  with  25  grains  of  the  best  quality  of  dry  pow- 
der, and  rested  upon  the  cover  the  knob,  C,  of  a  24-pd. 
gun,  whose  weight  was  8,081  lbs.  Notwithstanding  its 
great  strength,  the  eprouvette  was  burst  at  the  first  fire 
into  two  pieces ;  and  the  24-pdr.  was  raised.  Rumford 
endeavored  to  show  from  the  weight  thus  raised,  that  the 
pressure  of  the  gases  on  the  sides  of  the  eprouvette  was 
greater  than  10,000  atmospheres.  He  further  attempted 
to  show,  that  as  the  tenacity  of  good  iron  is  equal  to 
4,231  times  the  pressure  of  the  atmosphere  on  the  same 
surface,  and  as  the  surface  of  rupture  was  13  times  that 
of  the  bore,  the  force  necessary  to  produce  the  rupture 
of  the  eprouvette  must  have  been  13x4,231,  or  55,003 
atmospheres. 

There  are  circumstances  attending  this  experiment 
which  should  be  taken  into  account,  and  which  will 
very  materially  diminish  this  result.  They  are,  the 
diminution  of  the  tenacity  of  the  iron,  due  to  heating 
the  eprouvette  to  produce  explosion,  and  the  incorrect 
method  by  which  Rumford  estimated  the  strength  of  a 
hollow  cylinder  subjected  to  a  strain  of  expansion. 

33.  Relation  between  density  and  force.  Experi- 
ments were  continued,  with  a  similar  apparatus,  to  de- 
termine the  relation  between  the  density  and  the  expan- 
sive force  of  fired  gunpowder.  The  capacity  of  the 
eprouvette  was  nearly  25  grains.  It  was  fired  with  vari- 
ous charges  from  1  up  to  18  grains;  and  the  expansive 
force  of  each  discharge  was  determined  by  the  smallest 
weight  necessary  to  close  the  orifice  against  the  escape 


DENSITY   AND   FORCE.  57 

of  the  gas.  With,  the  results  of  85  trials  a  table  was 
formed,  from  which  a  curve  was  constructed  which  ex- 
presses the  relation  between  the  density  and  expansive 
force  of  fired  gunpowder,  from  1  to  15  grains.  By 
analogy  and  calculation,  this  curve  was  continued  up  to 
a  charge  of  24  grains ;  and  for  the  density  correspond- 
ing to  this  charge,  the  pressure  was  found  to  be  29,1 7  8 
atmospheres. 

This  pressure  is  much  greater  than  that  developed 
in  the  explosion  of  projectiles  and  mines,  owing  to  the 
low  temperature  of  the  surrounding  surfaces,  and  the 
large  amount  of  heat  which  they  absorb.  It  is  the  same 
with  cannon,  for  the  most  rapid  firing  does  not  raise  the 
temperature  of  the  bore  above  210  Fahr.,  which  is  much 
below  that  of  the  eprouvette.  Besides,  the  powder  does 
not  completely  fill  the  space  in  rear  of  the  ball ;  and, 
as  powder  burns  progressively,  this  space  is  enlarged 
before  the  gases  are  completely  developed,  and  conse- 
quently their  density  is  diminished.  There  is  also  a  loss 
of  force  by  the  escape  of  the  gases  through  the  windage 
and  vent. 

The  following  equation  expresses  the  relation  found 
to  exist  between  the  density  and  expansive  force  of 
charges  of  gunpowder,  from  1  to  15  grains,  fired  in  an 
eprouvette  the  capacity  of  which  was  25  grains,  or  in 
other  words,  for  charges  in  which  the  densities  vary 
from  .04  to  .6  : 

p=  1.841  (905dy+0M2d; 

in  which  p  represents  the  pressure  in  atmospheres,  and 
d  the  density  of  the  inflamed  products. 

It  will  be  seen  from  this  equation,  that  the  pressure 


58 


GUNPOWDER. FORCE. 


+tA 


increases  more  rapidly  than  the  density,  since  the  expo- 
nent of  the  density  is  greater  than  unity. 

The  density  of  the  gases  is  equal  to  the  weight  of  the 
powder  burned  divided  by  the  space  occupied  by  the  gases. 
By  substituting  this  in  the  equation,  we  can  determine 
the  pressure  exerted  at  any  given  instant  of  the  com- 
bustion. 

Although  this  relation  is  deduced  for  a  particular 
kind  of  powder,  it  may  be  used  for  all  service- powders 
and  service-charges  without  serious  error,  since  the  actual 
amount  of  gaseous  products  is  nearly  the  same  for  all, 
and  the  densities  of  the  highest  service-charges  never 
exceed  0.6*    Z^<t-rf4* 

34.  Force  of  powder  when  inflammation  is  instanta- 
neous. If  the  size,  form,  and  density  of  the  grains  of  a 
charge  of  powder,  the  velocity  of  combustion,  and  the 


*  The  accuracy  of  Rumford's  formula  has  been  lately  verified  by  a  series  of 
experiments  made  by  Captain  Rodman.  The  apparatus  used  by  this  officer  con- 
sisted of  a  very  thick  cast-iron  shell,  to  which  was  attached  an  indenting  piston  for 
determining  the  pressure  on  the  inner  surface,  or  powder  cavity  of  the  shell. 

The  following  table  shows  the  pressures  calculated  by  the  formula  and  the  pres- 
sures obtained  by  the  experiments,  for  three  different  densities : 


Density                1            Pressure  by 
tensity.                  Rumford's  Formula. 

Pressure  by 
Rodman's   Experiments. 

1,290  lbs. 
2,900    " 
3, 100    " 

1,066  lbs. 
2,525    " 
3,220    " 

The  lesser  pressure  obtained  by  Rodman's  experiments  may  be  in  a  great  measure 
explained  by  the  facts,  that  the  shell  was  not  heated,  but  fired  with  a  friction  tube, 
and  that  the  gas  was  allowed  to  escape  through  the  vent.  Further  experiments 
were  made  which  show  that  so  long  as  the  volume  of  the  charge  bears  the  same 
proportion  to  the  space  in  which  it  is  fired,  the  pressure  on  the  unit  of  surface 
remains  the  same,  no  matter  what  may  bo  the  amount  of  the  charge.  This  follows 
also  from  Rumford's  formula,  since  the  value  of  p  is  not  affected  so  long  as  d  remains 
the  same. 


FOKCE.  59 

space  in  which  it  is  contained,  are  known,  we  can  deter- 
mine the  density  of  the  gaseous  products  at  any  partic- 
ular moment  of  combustion.  For  this  purpose,  take  the 
case  in  which  the  inflammation  of  the  whole  charge  is 
considered  instantaneous,  and  let 

P  be  the  weight  of  the  charge, 

d'  the  density  of  the  composition  of  which  the 

powder  is  made, 
J^the  space  in  which  the  gases  expand, 
t!  the  time  of  combustion  of  a  single  grain, 
t  the  time  since  the  combustion  began, 
d  the  density  of  the  gases  at  a  given  instant. 

According   to    section    29,   the   weight   of   powder 

remaining  after  a  time,  t,  will  be  equal  to  P(  1 )  , 

P  /        A3 
and    the  volume    will    be    equal    to  -^(1— — J;    the 

weight  of  gaseous  products  evolved  will  be  equal  to 

P(  1  —  ( 1 )  ) ;  and  their  density  will  be  equal  to 

this  quantity  divided  by  the  space  V,  diminished  by 
the  space  occupied  by  the  powder  unburnt  at  the  end 
of  the  time  t. 

Or, 


P 
V 


fc-      j 


(-H)) 


Let  K  represent  the  ratio  of  the  weight  of  powder 
which  would  fill  the  space  V,  to  the  weight  of  the 
charge  P,  and  D  the  gravimetric  density,  or  weight 


60  GUNPOWDER. — FORCE. 

of  a  unit  of  volume  of  powder,  we  shall  have  the  equa- 
tion, 

and  the  formula  for  the  density  of  the  gaseous  products 
becomes, 

If  the  charge  fill  the  entire  space  V,  K—\  and 

-hi? 

When  the  grains  are  consumed,  £=£',  and^=—  ;  and 

Having  determined  the  mean  density  of  the  gaseous 
products  at  any  instant  of  the  combustion,  we  can  de- 
termine the  pressure  exerted  on  the  enclosing  surfaces 
by  means  of  Eumford's  formula 

P=  1.841  (905dy*0M2d. 

This  value  of  P  supposes  that  the  entire  charge  is 
inflamed  at  the  same  time — a  supposition  that  is  not 
strictly  correct,  except  for  small  and  lightly-rammed 
charges.  When  the  charge  is  large,  and  well-rammed, 
as  in  cannon,  it  is  necessary  to  take  into  consideration 
the  time  of  inflammation. 

35.  Density  when  the  inflammation  is  not  instan- 
taneous. In  a  majority  of  cases  the  preceding  formulas 
will  give  the  relation  between  the  density  and  expan- 


FORCE. 


61 


sive  force  of  gunpowder,  without  sensible  error;  but 
when  the  grains  are  small,  and  the  charge  is  com- 
pressed by  ramming,  the  interstices  are  diminished  in 
size,  and  the  inflammation  is  comparatively  less  rapid ; 
besides,  the  size  and  form  of  the  charge  exert  an  in- 
fluence which  increases  with  its  length.  It  is  proposed, 
therefore,  to  modify  the  formulas,  and  adapt  them  to 
the  most  general  case,  by  considering  the  inflammation 
progressive. 

Take  a  charge  of  powder,  of  any  form  whatever,  and 
consider  it  ignited  at  the  point  A,  the 
inflammation  will  reach  the  surface  of 
the  concentric  zone  J3,  the  radius  of 
which  is  tv,  in  the  time  t,  v  being  the 
velocity  of  inflammation.  There  will  be 
portions  of  the  charge  situated  within 
this  zone  which  the  flame  will  not  have 
reached  ;  others  in  which  the  combustion 
is  completed ;  and  others,  between  these 
two,  in  which  the  inflammation  is  completed,  but  the 
combustion  is  only  partially  completed.     See  figure  7. 


yv 


wrm 


Fig.  1. 


The  extent  of  the  inflamed  zones  being  determined 
by  the  form  and  dimensions  of  the  charge,  exerts  a  great 
influence  on  the  development  of  the  gases,  and  conse- 
quently on  their  density. 

If  the  velocities  of  inflammation  and  combustion  be 
known,  the  quantity  of  gas  formed  from  each  zone  can 
be  calculated,  and  the  question  becomes  one  of  analysis. 


62  GUNPOWDER. FORCE. 

In  this  calculation,  the  integral  limits  which  refer  to  the 
extent  of  the  zones  are  determined  by  the  surface  of  the 
charge ;  and  those  which  refer  to  the  progress  of  the 
combustion  of  the  grains  will  be  the  point  of  ignition 
and  the  surface  of  inflammation;  or,  if  e  be  the  time  ne- 
cessary for  the  flame  to  reach  the  surface  of  the  zone,  the 
radius  of  which  is  x,  the  time  of  partial  combustion  of  a 
grain  of  this  zone  will  be  t—e,  and  its  complete  combus- 
tion is  expressed  by  the  relation  t—t'-\-Q. 

For  this  zone  the  density  of  the  gaseous  products  at 
the  instant  of  inflammation  will  be  <fcO,  and  when  com- 
pletely consumed  d=D. 

The  intermediate  values  may  be  determined  by  for- 
mula (1) 


7 
d=- 


K-  <W>i 


by  substituting  t—e  for  t,  and  supposing  JT=1,  should 
the  charge  completely  fill  the  space  in  which  it  is  burn- 
ed. Integrating  between  the  determined  limits,  we  ob- 
tain the  mean  density  of  the  gases  developed. 

The  solution  of  this  question,  in  a  general  sense,  is 
very  difficult,  and  requires  the  aid  of  the  differential 
calculus.  There  are  particular  cases,  however,  where 
the  solution  is  not  difficult ;  for  instance,  where  the 
charge  is  of  cylindrical  form  and  is  placed  at  the  bottom 
of  the  bore  of  a  gun. 

36.  Calculation  of  the  den§ity  of  a  charge  of  cylin- 
drical form.  Although  the  charge  of  a  gun  is  ignited 
at  the  rear  and  upper  portion,  we  may  consider  that  all 
portions  of  the  circular  layer  at  the  bottom  are  inflamed 


FORCE.  63 

at  once,  and  that  the  inflammation  spreads  by  parallel 
layers  throughout  its  extent.  The  space  at  the  bottom 
of  the  bore,  and  the  escape  of  gas  through  the  vent, 
favor  this  supposition. 

Let  L  represent  the  total  length  of  the  charge,  and 
Q'  the  time  necessary  for  the  inflammation  to  pass  over 
this  length.  Let  us  assume  that  e'—nt\  t'  being  the 
time  necessary  for  the  combustion  of  a  single  grain  of 
the  charge ;  n,  therefore,  is  the  ratio  of  these  times. 

L         L 

The  velocity  of  inflammation  will  be  -7,  or  — ,;     and 

—  will  represent  the  portion  of  the  charge  inflamed  in 
nt' 

the  time  t     The  length  of  the  charge  which  will  be 

consumed  (and  no  portion  can  be  entirely  consumed 

unless  t>f)  will  be  (t—f) — }]  and  the  thickness  of  the 
burning  layer  will  be  the  difference  between  these  two 

quantities,  or  —  ;   which  is  constant. 
n 

If  the  area  of  a  section  of  the  charge,  perpendicular 
to  its  axis,  be  taken  as  the  unit  of  surface,  the  volumes 
may  be  represented  by  their  lengths.  Divide  the 
length  of  the  burning  portion  into  a  number,  A,  of 
smaller  sections,  the  length  of  one  of  the  smaller  sec- 
tions will  be  equal  to  —  ;  if  A  be  very  large,  the  grains 

of  each  very  small  section  may  be  considered  in  the 
same  stage  of  combustion,  and  the  radii  of  the  consumed 
layers  in  each  grain  of  the  small  sections  will  be 
represented  in  parts  of  the  primitive  radius,  as  fol- 
lows : — 


64  GUNPOWDEK. FOKCE. 

For  the  1st,  2d,     3d.      .     .     A— 2,  A— 1,  A,   sections. 
A  A-l  A-2  _3       _2_       1_ 

A'    h  '    A  '   "    '      V      A'     A' 

The  radii  of  the  burning  grains  will  be, 

1    2  A-3  h— 3  A-l. 

"'   A    A'      "     '   "TT1     A    '      A  ' 
and  the  corresponding  volumes  of  the  unburnt  portions 
will  be  represented  by. 

/1V    /A8  /A-3V    /A-2V    /A-1V 

The  volumes  burned  will  be  represented  by, 

If  D  represent  the  gravimetric  density  of  the  pow- 
der, the  weight  of  each  small  section  will  be  — -D,  and 

the  weight  of  the  gaseous  products  in  all  the  sections 
will  be 

LjyU       l»+28+38+48...+(A-l)3)  . 
nfi°Y~-         ¥ }' 

but  we  know  in  general  terms  that 

l3+23+38...^,  or2z8=^±iY; 

therefore  the  sum  of  the  weights  of  the  gases  formed 
will  be, 

If  we  suppose  h,  the  number  of  sections,  to  be  infi- 
nite, the  above  expression  will  reduce  to 
LD  .        .       LD 


•(i-0= 


3. 


•'     T  n 


FORCE.  65 

The  portion  of  the  charge  entirely  consumed  being 

^ £  t ft 

equal  to  —jrL,  its  weight  will  be  — y-ZD,  and  the 

total  weight  of  gaseous  matter  developed  will  be, 

nt  '       n        nt  \       4  / 

The  space  which  they  occupy  is  equal  to  the  volume 
of  the  inflamed  portion  of  the  charge,  diminished  by 
the  volume  of  the  unburned  grains  at  the  end  of  the 

time  t ;  the  volume  of  the  burning  powder  is  — ,  and 

n 

its  weight  is  —D.     The  weight  of  the  portion  burned 

being  equal  to  f- ;    that   which   remains   unburned 

n 

will  be  equal  to  J- ,  and  the  density  of  the   grains 

being  d\  their  volume  will  be  equal  to  \  — -      The 

nd 

volume  into  which  the  gases  expand  will  consequently 

be  equal  to 

tZ«LD 

nt'     4  nd' ' 
Finally,  the  mean  density  of  the  gases  at  the  instant 
t  will  be, 


tL_  i  ZIJ  tTB_ 

nt'     T   nd'  4d 

From  this  it  will  be  seen  that  the  density  is  indepen- 
dent of  the  velocity  of  inflammation  and  length  of  the 
charge.      The  formula,  however,  can  only  be  applied 


66  GUNPOWDEE. FOECE. 

from  the  instant  t=t'  to  that  in  which  t=d'  —  t\  that  is 
to  say,  so  long  as  there  exists  a  portion  of  the  charge  in 
which  the  combustion  is  ceasing  on  its  posterior  surface, 
and  commencing  on  its  anterior  surface. 

Without  committing  a  serious  error,  we  can,  how- 
ever, apply  the  formula  when  t—\t\  because,  in  taking 
the  sum  of  the  cubes  ()+l8+23+38+. . .+  (A-l)3 
from  1  to  (A— l)8  it  will  only  be  necessary  to  take  it 

//A  8 

from    |~J    to   (h—  l)3,  which  makes  an  error  equal  to 

seen  by  replacing  A  by  -  in  the  expression  -J  — ^ '  !■  . 

If  the  section  of  the  charge,  instead  of  being  equal 

to  the  section  of  the  bore  of  the  gun,  is  only  -=,  the 

gases  being  developed  freely  in  a  space  K  times  greater, 
the  density  D  will  be  diminished  in  an  inverse  ratio, 
and  we  shall  have 


KtJD 


4tKd' 

37.  Application  to  practice.  Thus  it  will  be  seen 
that  the  density,  and  consequently  the  expansive  force 
of  fired  gunpowder  can  be  determined  at  each  instant 
of  combustion,  either  in  the  case  in  which  the  inflamma- 
tion is  considered  instantaneous,  or  when  considered 
progressive. 

The  accuracy  of  the  formulas  was  verified  in  France 
some  years  since,  in  the  course  of  a  series  of  experiments 


PRACTICAL    RESULTS.  67 

to  determine  the  influence  which  the  size  and  density 
of  grains  of  powder  exert  upon  the  initial  velocity  of  a 
projectile. 

There  were  six  different  sizes  of  grains  tried,  viz. : — 
.26  in.,  .21  in.,  .18  in.,  .15  in.,  .10  in.  (cannon),  .05  in. 
(musket) ;  of  each  size  there  were  six  different  densi- 
ties, viz. : — 1.3,  1.4,  1.5,  1.6,  1.7,  1.8,  and  four  different 
modes  of  manufacture,  making  144  varieties  of  powder 
in  all.  The  instruments  used  were  the  ballistic  pendu- 
lum, the  4-pdr.  gun  pendulum,  the  mortar  eprouvette, 
and  the  infantry  musket. 

The  results  of  calculation  and  direct  experiment  show 
a  remarkable  agreement,  and  may  be  summed  up  as  fol- 
lows, viz.: — 

1.  With  the  4-pdr.  gun  the  high  densities  gave 
greater  velocities  when  combined  with  the  smallest 
grains,  and  vice  versa,  the  low  densities  gave  greater 
velocities  when  combined  with  the  largest  grains.  The 
grains  which  gave  the  highest  velocities  possessed  me- 
dium size  and  density,  or  a  density  of  1.5  combined 
with  a  diameter  of  0.18  in. 

2.  With  the  mortar  eprouvette,  which  fired  a  smaller 
charge  than  the  4-pdr.  gun,  the  fine-grained  powder 
gave  almost  invariably  greater  velocities  than  the 
coarse.  For  a  grain  of  .1  in.  (or  cannon  size),  the  low- 
est densities  gave  the  best  results,  and  for  a  grain  of  .05 
in.  (or  musket  size),  the  highest  densities  gave  the  best 
results. 

3.  With  the  infantry  musket,  and  a  still  smaller 
charge,  the  superiority  of  fine  grains  was  more  marked 
for  all  densities,  and  particularly  so  for  the  least. 

It  would  appear  from  the  foregoing,  that  the  proper 


68  GUNPOWDER. GUN-COTTON. 

size  and  density  of  grains  of  powder  will  depend  on  the 
weight  of  the  projectile  to  be  moved,  the  size  of  the 
charge,  and  the  diameter  and  length  of  the  bore  in 
which  it  is  to  be  burned ;  or,  in  other  words,  cannon 
powder  should  have  a  coarser  grain  and  higher  density 
than  that  intended  for  use  in  small -arms. 


GUN-COTTON. 

38.  Gun-cotton,  or  pyroxiie.  The  action  of  nitric  acid 
on  such  vegetable  substances  as  saw-dust,  linen,  paper, 
and  cotton,  is  to  render  them  very  combustible.  In 
their  natural  state  these  substances  are  almost  entirely 
composed  of  lignine,  the  constituents  of  which  are  oxy- 
gen, hydrogen,  and  carbon ;  nitric  acid  furnishes  nitro- 
gen, a  substance  which  enters  into  the  composition  of 
nearly  all  explosive  bodies. 

Gun-cotton  was  discovered  by  Prof.  Schonbein,  and 
published  to  the  world  in  1846.  His  method  of  pre- 
paring it  consists  in  mixing  three  parts  of  sulphuric 
acid,  sp.  grav.  1.85,  with  one  part  of  nitric  acid,  sp.  gr. 
1.45  to  1.50 ;  and  when  the  mixture  cools  down  to  be- 
tween 50°  and  60°  Fahr.,  clean  rough  cotton,  in  an  open 
state,  is  immersed  in  it ;  when  soaked,  the  excess  of  acid 
is  poured  off,  and  the  cotton  pressed  tightly  to  remove 
as  much  as  possible  of  what  remains.  The  cotton  is 
then  covered  over  and  left  for  half  an  hour,  when  it  is 
again  pressed,  and  thoroughly  washed  in  running  water 
to  remove  all  free  acid.  After  being  partially  dried  by 
pressure,  it  is  washed  in  an  alkaline  solution  made  by 
dissolving  one  ounce  of  the  carbonate  of  potash  in  a 
gallon  of  water.     The  free  acid  being  thus  expelled,  it 


GUN-COTTON.  69 

is  placed  in  a  press,  the  excess  of  alkaline  solution  ex- 
pelled, and  the  cotton  left  nearly  dry.  It  is  then 
washed  in  a  solution  of  pure  nitrate  of  potash,  one 
ounce  to  the  gallon,  and  being  again  pressed,  is  dried  at 
a  temperature  of  from  150°  to  170°. 

The  sulphuric  acid  has  no  direct  action  on  lignine,  its 
use  in  the  preparation  of  pyroxile  being  to  retain  the 
water  abstracted  from  the  cotton,  and  prevent  the  solu- 
tion of  the  compound,  which  would  take  place,  to  a 
greater  or  less  extent,  in  nitric  acid  alone. 

Cotton,  in  its  conversion  into  an  explosive  substance, 
increases  very  considerably  in  weight,  owing  to  the  for- 
mation of  a  new  and  distinct  chemical  compound. 

Gun-cotton,  when  properly  prepared,  explodes  at  a 
temperature  of  about  380°  Fahr.  It  will  not,  therefore, 
ignite  gunpowder,  when  loosely  poured  over  it. 

Under  ordinary  circumstances,  the  electric  spark  will 
not  explode  it ;  but  if  the  fluid  be  retarded  in  its  prog- 
ress by  being  passed  over  the  surface  of  a  string  mois- 
tened with  common  water,  and  in  contact  with  the  cot- 
ton, explosion  will  follow. 

From  the  experiments  of  Major  Mordecai,  made  at 
Washington  arsenal,  in  1846,  the  following  facts  regard- 
ing the  use  of  this  substance  in  the  military  service, 
were  ascertained: — 

1.  The  projectile  force,  when  used  with  moderate 
charges  in  musket  or  cannon,  is  equal  to  that  of  about 
twice  its  weight  of  the  best  gunpowder. 

2.  When  compressed  by  hard  ramming  (as  in  filling 
a  fuze),  it  burns  slowly. 

3.  By  the  absorption  of  moisture,  its  force  is  rapidly 
diminished,  but  it  is  restored  by  drying. 


70  GUNPOWDEK. GUN-COTTON. 

4.  Its  explosive  force,  or  bursting  effect,  is  in  a  high 
degree  greater  than  that  of  gunpowder.  In  this  respect 
the  nature  of  gun-cotton  assimilates  much  more  to  that 
of  the  fulminates  than  to  gunpowder.  It  is,  conse- 
quently, well  adapted  for  many  purposes  in  mining. 

5.  Gun-cotton,  well  prepared,  leaves  no  perceptible 
stain  when  a  small  quantity  is  burnt  on  white  paper. 

6.  It  evolves  little  or  no  smoke,  as  the  principal  resi- 
due of  its  combustion  is  water  and  nitrous  acid ;  the  lat- 
ter is  made  sensible  by  its  odor,  and  by  its  effects  on  the 
barrel  of  a  gun,  which  will  soon  be  corroded  by  it,  if 
not  wiped  after  firing. 

7.  In  consequence  of  the  quickness  and  intensity  of 
action  of  gun-cotton,  when  ignited,  it  cannot  be  used 
with  safety  in  our  present  fire-arms.  An  accident  of 
service,  such  as  that  of  inserting  two  charges  into  a 
musket  before  firing  (which  frequently  occurs),  would 
cause  the  bursting  of  the  barrel ;  and  it  is  probable  that 
the  same  result  would  be  produced  by  regular  service 
charges,  repeated  a  moderate  number  of  times. 

Within  a  few  years,  attempts  have  been  made  to  in- 
troduce gun-cotton  into  the  Austrian  field-artillery,  as  a 
substitute  for  gunpowder;  and  for  this  purpose  several 
batteries  of  short,  thick  bronze  guns  have  been  prepared 
for  service. 


^  d  ** 


PROJECTILES.  71 


CHAPTER  II. 
'^tt*         PROJECTILES. 

39.  Definition.  A  projectile  is  intended  to  reach  and 
strike,  pass  through,  or  destroy,  a  distant  object;  the 
effect  of  a  projectile  varies  with  its  form  and  the  mate- 
rial of  which  it  is  composed. 

To  destroy  an  object  against  which  it  is  thrown,  a 
projectile  should  have  certain  hardness  and  tenacity;  if 
it  be  softer  and  less  tenacious  than  the  object,  it  will 
spread  out  laterally,  or  break  into  pieces,  and  presenting 
a  greater  surface,  will  meet  with  greater  resistance,  and 
consequently  penetrate  less  than  if  it  had  preserved  its 
primitive  form.  Great  density  is  also  favorable  to 
penetration,  inasmuch  as  it  gives  a  projectile  a  greater 
mass  for  an  equal  surface. 

40.  Material!.  Stone,  lead,  wrought  and  cast  iron 
are  materials,  each  possessing  peculiar  advantages  for 
projectiles,  according  to  the  circumstances  under  which 
they  are  fired,  and  the  objects  against  which  they  are 
used. 

Stone.  Stone  projectiles  were  used  before  the  inven- 
tion of  gunpowder,  and  very  generally  after  it,  until  the 
year  1400,  when  the  French  made  them  of  cast  iron. 

The  defects  of  stone  as  a  material  for  projectiles,  are 
a  want  of  density  and  tenacity,  which  requires  it  to  be 
used  in  large  masses,  and  fired  with  comparatively  small 
charges  of  powder.     The  effect  of  stone  balls  against 


72  PROJECTILES. 

the  walls  of  ancient  cities  was  very  great,  but  against 
modern  fortifications,  where  the  walls  are  sustained  by 
large  masses  of  earth,  their  effect  is  very  slight.  Until 
quite  lately,  bronze  guns,  throwing  stone  balls  of  enor- 
mous calibre,  were  used  by  the  Turks  in  defending  the 
passage  of  the  Dardanelles.  It  is  stated  that  when  the 
English  fleet,  under  Admiral  Duckworth,  forced  the 
passage  of  these  straits,  a  stone  ball  weighing  800  lbs. 
struck  and  nearly  destroyed  the  English  admiral's  ship, 
and  that  one  hundred  men  were  killed  and  wounded 
by  it. 

Lead.  Lead  as  a  material  for  projectiles,  possesses 
the  essential  quality  of  density ;  but  it  is  too  soft  to  be 
used  against  very  resisting  objects,  since  it  is  flattened 
even  against  water. 

From  its  softness  and  fusibility,  large  projectiles  of 
this  material  are  liable  to  be  disfigured,  and  partially 
melted,  by  the  violent  shock  and  great  heat  of  large 
charges  of  powder.  Its  use  is  chiefly  confined  to  small- 
arms  and  case-shot,  which  are  generally  directed  against 
animate  objects.  These  defects  of  lead  may  be  correct- 
ed, in  a  measure,  by  alloying  it  with  tin,  antimony,  <fcc. 

Wrought  iron.  When  great  strength  and  density, 
combined,  are  required  in  a  projectile,  wrought  iron  may 
be  used,  but  it  is  generally  attended  with  considerable 
expense. 

Cast  iron.  The  introduction  of  cast  iron,  for  large 
projectiles,  was  an  important  step  in  the  improvement 
of  artillery,  as  it  unites  in  a  greater  degree  than  any 
other  material,  the  essential  qualities  of  hardness, 
strength,  density,  and  cheapness ;  it  is  exclusively  used 
for  this  purpose  in  the  United  States'  service. 


CLASSIFICATION.  73 

Compound.  Compound  projectiles  are  sometimes 
made  so  as  to  combine  the  good  and  correct  the  bad 
qualities  of  different  metals.  Thus,  at  the  siege  of 
Cadiz,  cast-iron  shells  filled  with  lead,  forming  projec- 
tiles of  great  strength  and  density,  were  thrown  from 
mortars  to  a  distance  of  three  miles  and  three  quarters. 

For  rifle-cannon,  projectiles  are  made  occasionally  of 
cast  iron,  and  covered  with  a  soft  coating  of  lead,  or 
other  soft  metal,  to  obviate  the  serious  results  that 
might  arise  from  the  wedging  of  the  flanges  in  the 
grooves  of  the  gun.  Such  is  the  construction  of  Arm- 
strong's projectile  in  England,  and  Sawyer's  and  others, 
in  this  country. 

In  the  rifle-cannon  lately  used  by  the  French  army  in 
Italy,  it  is  stated  that  the  flanges  which  projected  into 
the  grooves  of  the  bore  were  made  of  tin. 

Considerable  success  has  also  been  attained  in  uniting 
cast  iron  and  wrought  iron,  and  cast  iron  and  soft  metal, 
in  such  manner  as  to  attain  the  strength  of  one  metal, 
and  the  softness  and  expansibility  of  the  other. 

41.  cias§iflcation.  Projectiles  may  be  classified  ac- 
cording to  their  form,  as  spherical  and  oblong. 

Spherical  projectiles.  Spherical  projectiles  are  com- 
monly used  in  smooth-bored  guns,  and  for  this  purpose 
possess  certain  advantages  over  those  of  an  oblong 
form :  1.  They  present  a  uniform  surface  to  the  resist- 
ance of  the  air  as  they  turn  over  in  their  flight.  2.  For 
a  given  weight  they  offer  the  least  extent  of  surface  to 
the  resistance  of  the  air.  3.  The  centres  of  figure  and 
inertia  coincide.  4.  They  touch  the  surface  of  the  bore 
at  only  one  point;  they  are  therefore  less  liable  to 
wedge  in  the  bore,  and  endanger  the  safety  of  the  piece. 


74  PROJECTILES. 

5.  Their  rebounds  on  land  and  water  being  certain  and 
regular,  they  are  well  suited  to  rolling  and  ricochet 
firing. 

Oblong  projectiles.  The  great  improvements  which 
have  been  made  within  the  last  few  years  in  the  accu- 
racy and  range  of  cannon  and  small-arms,  consist  simply 
in  the  use  of  the  oblong  instead  of  the  spherical  form 
of  projectile. 

The  superiority  of  the  oblong  form  has  been  long 
known,  and  for  many  years  used  in  the  sporting  rifles 
of  this  country;  but  serious  obstacles  have  always 
stood  in  the  way  of  its  general  adoption  into  the  mili- 
tary service. 

To  attain  accuracy  of  flight  and  increase  of  range  with 
an  oblong  projectile,  it  is  necessary  that  it  should  move 
through  the  air  in  the  direction  of  its  length.  Though 
experience  would  seem  to  show  that  the  only  sure 
method  of  effecting  this,  is  to  give  it  a  rapid  rotary 
motion  around  its  long  axis  by  the  grooves  of  the  rifle, 
numerous  trials  have  been,  and  are  now  being  made,  to 
produce  the  same  effect  with  smooth-bored  arms. 

Centre  of  gravity,  <&c.  One  of  the  simplest  plans 
used  for  this  purpose,  is  to  place  the  centre  of  gravity, 
or  inertia,  in  advance  of  the  centre  of  figure,  or  resist- 
ance. If  these  points  be  situated  in  the  long  axis  of 
the  projectile,  as  they  should  be,  the  forces  of  propul- 
sion and  resistance,  which  act  in  opposite  directions, 
will  cause  it  to  coincide  with  the  line  of  flight. 

This  plan  was  tried  on  a  hollow  projectile  in  the  time 
of  Louis  XIV.,  by  dividing  the  cavity  into  two  com- 
partments by  a  partition,  and  filling  the  front  one  with 
bullets,  and  the  rear  one  with  powder ;   but  the  flight 


SOLID    PKOJECTILES.  75 

of  these  projectiles  was  uncertain  and  irregular,  and  it 
was  observed  that  some  of  them  burst  in*  the  air,  and 
that  others  struck  the  object  sidewise. 

Another  plan  of  this  kind,  proposed  by  Thiroux,  is 
to  make  the  projectile  very  long,  with  its  rear  portion 
of  wood,  and  its  point  of  lead  or  iron,  somewhat  after  the 
manner  of  an  arrow ;  but  it  does  not  appear  that  that 
method  has  ever  been  submitted  to  the  test  of  practice. 

Chain-ball.  To  arrest  the  motion  of  rotation  of  an 
oblong  projectile,  thrown  under  high  angles,  and  with 
a  moderate  velocity,  it  has  been  proposed  to  attach  a 
light  body  to  its  posterior  portion,  by  means  of  a  cord 
or  chain,  which  will  offer  a  resistance  to  the  flight  of 
the  projectile,  and  cause  it  to  move  with  its  point  fore- 
most. 

Nail-ball.  This  is  a  round  projectile,  and  has  an  iron 
pin  projecting  from  it  to  prevent  it  from  turning  in  the 
bore  of  the  piece. 

Grooved  balls.  Attempts  have  also  been  made  to  give 
an  oblong  projectile  a  motion  of  rotation  around  its 
long  axis,  by  cutting  spiral  grooves  on  its  base  for  the 
action  of  the  charge,  or  by  cutting  them  on  the  forward 
part  for  the  action  of  the  air.  These  plans  have  not 
succeeded  in  practice,  for  the  reason,  perhaps,  that  the 
projectile  naturally  turns  over  end  for  end,  and  the  air 
and  charge  do  not  act  on  the  grooves  with  sufficient 
promptness,  energy,  and  certainty  to  prevent  it. 

42.  Solid  shot.  Projectiles  may  be  further  classified 
according  to  their  structure  and  mode  of  operation,  as 
solid,  hollow  and  case  shot. 

Solid  projectiles.  Solid  projectiles  are  used  in  guns 
and  small-arms,  and  produce  their   effect  by  impact 


76  PROJECTILES. 

alone.  When  used  in  heavy  guns  they  are  known  as 
solid  shot,  round  shot,  or  shot.  They  are  made  of  cast 
iron,  and  on  account  of  their  great  strength  and  density, 
and  the  comparatively  large  charges  of  powder  with 
which  they  are  fired,  are  used  when  great  range,  accu- 
racy, and  penetration  are  required.  They  are  the  only 
projectiles  that  can  be  used  with  effect  against  very 
strong  stone  walls,  or  floating  batteries  covered  with 
wrought-iron  plates.  Solid  shot  for  guns  are  classified 
according  to  their  weight,  which,  in  the  United  States' 
land  service,  is  as  follows,  viz. : 

Field  service,  6  and  12  pounders. 

Siege  service,  12,  18,  and  24  pounders. 

Sea-coast  service,  32  and  42  pounders. 

Solid  shot  for  columbiads  are  classified  according  to 
the  diameter  of  the  bore,  as  8  and  10  inch  solid  shot. 

43.  Bullets.  The  object  of  small-arms  is  to  attain 
animate  objects ;  their  projectiles  are,  therefore,  made 
of  lead,  and  are  generally  known  as  bullets.  They  are 
both  round  and  oblong ;  but  in  consequence  of  the  great 
improvements  that  have  been  made  of  late,  in  adapting 
the  principle  of  the  rifle  to  small-arms,  the  oblong  ball 
is  now  very  generally  used  in  all  military  services,  the 
round  bullet  being  chiefly  retained  for  use  in  case-shot. 

Hound  bullets.  Round  bullets  are  denominated  by 
the  number  contained  in  a  pound ;  this  method  is  often 
used  to  express  the  calibre  of  small-arms ;  as,  for  in- 
stance, the  calibre  of  the  old  musket  was  17  to  the 
pound,  and  the  rifle  was  32.  In  1856,  these  two  calibres 
were  replaced  by  one  of  24  to  the  pound,  that  of  the 
new  rifle  musket.  The  number  is  sometimes  prefixed 
to  the  word  gauge,  in  which  case  the  rifle-musket  would 


SHELLS.  77 

be  called  a  24:-gauge  gun.  This  mode,  however,  is  prin- 
cipally used  to  designate  sporting  arms. 

The  oblong  bullet  is  denominated  by  its  diameter 
and  weight ;  for  instance,  the  new  rifle-musket  ball  has 
a  diameter  of  0.58  in.,  and  weighs  540  grains. 

Oblong  bullet.      The  oblong  bullet  at  present  used  in 

v~ v  the  United  States'  service,  is  composed 

/        \  of  a  cylinder  surmounted  by  a  conoid 

/  \  — the  conoid  being  formed  of  the  arcs 

I  ~~~~^p— ---._..  of  three  circles.  The  cylinder  has 
C  y  three  grooves  cut  in  it,  in  a  direction 

i  '  \f\  perpendicular  to  its  axis,  to  hold  the 

Fig.  9.  grease  necessary   for   lubricating  the 

bore  of  the  piece  in  loading,  and  possibly  to  guide  the 
bullet  in  its  flight,  after  the  manner  of  the  feathers  of 
an  arrow. 

A  conical  cavity  is  formed  in  the  bottom,  in  which 
the  gas  of  the  charge  expands,  and  forces  the  sides 
of  the  bullet  into  the  grooves  or  rifles  of  the  gun. 
From  these  grooves  it  receives  a  rotary  motion  around 
its  long  axis,  which  prevents  it  from  turning  over  in 
its  flight. 

44.  Sheiig.  Under  the  head  of  hollow  shot  are  includ- 
ed shells  for  guns,  howitzers,  and  mortars,  and  hand  and 
rampart  grenades.  These  projectiles  are  all  made  of 
cast  iron;  and  for  guns  and  field  howitzers  their  cali- 
bres are  expressed  by  the  weight  of  the  equivalent 
solid  shot,  as  12,  24,  and  32  pound  shells ;  and  for 
all  other  howitzers  and  mortars,  by  the  diameter  of 
the  bore  of  the  piece,  as  8  and  10  inch  shells. 

Shells  have  less  strength  to  resist  a  shock,  they  are 
therefore  fired  with  a  smaller  charge  of  powder,  than 


78  PKOJECTILES. SHELLS. 

solid  shot.  Their  weight,  and  consequent  mean  den- 
sity, is  generally  about  two-thirds  that  of  a  solid  shot 
of  the  same  size. 

Shells  act  both  by  impact  amd  explosion,  and  are 
used  against  animals  and  such  inanimate  objects  as 
will  not  cause  them  to  break  on  striking. 

The  principal  parts  of  a  spherical  shell  are :  1.  The 
canity — the  shape  of  which  is  similar  to  and  concentric 
with  the  exterior.  The  use  of  the  cavity  is  to  contain 
a  bursting  charge  of  powder,  if  the  object  be  merely 
to  destroy  by  explosion;  or  a  bursting  charge  and 
incendiary  composition,  if  the  object  be  to  destroy 
by  explosion  and  combustion  together.  The  size  of 
the  cavity  should  be  as  large  as  possible,  to  produce 
the  greatest  explosive  effect ;  but  as  the  shell  should 
have  sufficient  strength  to  resist  the  shock  of  the  dis- 
charge, and  sufficient  weight  to  overcome  the  resistance 
of  the  air,  the  size  of  the  cavity  will  necessarily  be  sub- 
ordinate to  these  conditions,  which  fix  the  thickness  of 
the  metal.  2.  The  fuze-hole,  which  is  used  in  inserting  the 
bursting  charge,  and  to  hold  the  fuze  which  communi- 
cates fire  to  it.  As  the  presence  of  the  fuze-hole  dimin- 
ishes the  effect  of  the  bursting  charge,  the  diameter  of 
its  orifice  should  be  as  small  as  possible.  3.  The  ears 
are  two  small  recesses  made  near  the  fuze-holes  of  all 
shells  larger  than  a  42-pound er,  for  the  purpose  of  in- 
serting the  "  hooks,"  and  lifting  the  shells  up  to  the 
bore  of  the  piece  in  loading.  A  small  hole  is  sometimes 
made  in  the  upper  hemisphere  of  shells,  for  the  purpose 
of  charging  them  after  the  fuze  is  driven  ;  but  late  im- 
provements in  the  construction  of  the  fuze  allow  it  to  be 
dispensed  with,  so  that  the  powder  can  now  be  poured 


OF  THE 

UNIVERSIl 


GRENADES. 


directly  through  the  fuze-plug,  and  the  charging  can  be 
deferred  until  the  moment  of  loading. 

Fig.  10  represents  a  mortar-shell,  and  fig.  11  a  shell 
used  in  a  gun  or  sea-coast  howitzer.  The  mortar-shell 
is  fired  with  a  lighter  charge  of  powder  than  the  gun- 
shell,  and  has  therefore  less  thickness  of  metal. 

The  fuze-hole  of  the  gun-shell,  is  reinforced  with 
metal,  so  that  the  fuze  will  not  be  driven  in  by  the  force 
of  the  discharge.  This  reinforce  serves,  in  a  measure,  to 
compensate  for  the  metal  taken  out  of  the  fuze-hole,  and 
renders  the  shell  more  concentric. 


a'.  .Fuze-hole. 

b.  .Reinforce. 

c.  .Cavity. 

d.  .Sides,  or  thick- 

ness of  metal. 
e . .  Ears. 

Kg.  10. 


Fig.  11. 


45.  Grenades.  The  hand  grenade,  as  its  name  indi- 
cates, is  a  projectile  thrown  from  the  hand,  against 
troops  in  mass. 

The  particular  projectile  used  for  this  purpose,  in 
our  service,  is  the  6-pounder  spherical  case-shot. 

Rampart  Grenade.  Rampart  grenades  are  intended 
to  be  rolled  down  the  rampart  of  a  work,  to  protect  a 
breach  against  the  attack  of  a  storming  column.  Shells 
of  any  size  will  answer  for  this  purpose,  and  particu- 
larly those  which  are  unserviceable  for  ordinary  pur- 
poses. 

Grenades  are  filled  with  a  bursting  charge,  and  are 


80 


PROJECTILES. CASE-SHOT. 


armed  with  a  short  fuze,*  which  is  lighted  by  a  match 
in  the  hands  of  the  grenadier  immediately  before  it  is 
thrown.  They  act  by  the  force  of  their  explosion 
alone. 

46.  Ca§e-shot.  Case-shot  are  a  collection  of  small  pro- 
jectiles enclosed  in  a  case  or  envelope.  The  envelope  is 
intended  to  be  broken  in  the  piece  by  the  shock  of  the 
discharge,  or  at  any  point  of  its  flight,  by  a  charge  of 
powder,  enclosed  within  it ;  in  either  case,  the  contained 
projectiles  continue  to  move  on  after  the  rupture,  but 
scatter  out  into  the  form  of  a  sheaf  or  cone,  so  as  to 
cover  a  large  surface  and  attain  a  great  number  of  ob- 
jects. These  projectiles  can  only  be  used  with  effect 
against  animate  objects  situated  at  a  short  distance  from 
the  point  of  rupture. 

The  three  principal  kinds  of  case-shot  in  use  are 
grape \  canister,  and  spherical  case-shot,  or  shrapnel.  They 
are  adapted  to  all  guns  and  howitzers 
below  those  of  10- inch  calibre,  and  re- 
ceive their  name  from  the  pieces  in 
which  they  are  used. 

Grape-shot.  A  grape-shot  is  com- 
posed of  nine  small  cast-iron  balls,  dis- 
posed in  three  layers  of  three  balls 
each.  Formerly  the  balls  were  held 
together  by  a  covering  of  canvas  and 
network  of  twine;  but  the  present 
method  is  more  simple  and  durable. 


*  Ketchum's  hand  grenade,  which  has  lately  been  introduced  into  the  American 
service,  is  a  small,  oblong  percussion  shell,  which  explodes  on  striking  a  slightly 
resisting  object.  To  prevent  accidents,  the  "plunger,"  or  piece  of  metal  which 
communicates  the  shock  to  the  percussion  cap  is  not  inserted  in  its  place  until  the 
moment  before  the  grenade  is  thrown. 


CASE-SHOT. 


81 


The  parts  of  a  stand  of  grape  are,  two  plates,  #,  a,  see 
Fig.  12,  for  the  top  and  bottom  layers;  two  rings, Z>,  b, 
for  the  intermediate  layer,  and  a  screw-bolt,  <?,  which 
passes  through  the  plates  and  unites  the  whole.  A  han- 
dle is  formed  by  passing  a  piece  of  rope-yarn  through 
two  holes  in  the  upper  plate,  and  tying  the  ends  into 
knots  to  prevent  them  from  pulling  out. 

Grape-shot  are  used  in  all  except  the  field  and  moun- 
tain services. 

Canister-shot*  A  canister-shot  for  a  gun  contains  27 
small  cast-iron  balls,  arranged  in  four  layers,  the  top  of 
6,  and  the  remainder  of  7  each.  A  canister-shot  for  a 
howitzer  contains  48  small  iron  balls,  in  4  layers  of  12 
each.  For  the  same  calibre,  it  will  be  seen  that  the 
balls  used  in  canister-shot  are  smaller  than  those  used 
in  grape-shot.  The  envelope  is  a 
tin  cylinder,  closed  at  the  bottom 
by  a  thick  cast-iron  plate,  and  at  the 
top  by  one  of  sheet-iron.  The  plates 
are  kept  in  place  by  cutting  the 
edges  of  the  cylinder  into  strips 
about  0.5  inch  long,  and  lapping 
them  over  the  plates.  To  give  more 
solidity  to  the  mass,  and  prevent 
the  balls  from  crowding  upon  each 
other  when  the  piece  is  fired,  the  interstices  are  closely 
packed  with  sawdust.  The  handle  is  made  of  wire, 
and  attached  to  the  thin  plate  at  the  top. 

Canister-shot  are  used  in  the  field,  mountain,  siege, 
and  sea-coast  services. 


c 

W> 

jo 

m 

Fior      13. 


*  The  balls  for  canister  for  bronze  rifle-guns  are  made  of  lead,  or  enclosed  in  a 
case  of  some  soft  material,  to  avoid  injury  to  the  surface  of  the  bore. 
6 


82  PROJECTILES. CASE-SHOT. 

It  is  stated  that  canister-shot  were  first  used  in  the 
defence  of  Constantinople,  about  the  middle  of  the  15  th 
century. 

Spherical  case-shot.  Though  projectiles  similar  to 
spherical  case-shot  were  used  in  France  as  early  as  the 
time  of  Louis  XIV.,  the  credit  of  perfecting  them  is 
due  to  Colonel  Shrapnel  of  the  British  army.  They 
were  first  successfully  used  by  the  English  against  the 
French,  in  the  Peninsular  war. 

The  envelope  in  the  spherical  case-shot,  is  a  thin  cast- 
iron  shell,  the  weight  of  which,  when  empty,  is  about 
one  half  that  of  the  equivalent  solid 
shot.  To  prepare  this  shot,  it  is 
first  filled  with  round  musket-balls, 
17  to  the  lb.,  and  the  interstices  are 
then  filled  up  by  pouring  in  melted 
sulphur  or  resin ;  the  object  of  which 
Fig.  14.  is  to  solidify  the  mass  of  bullets,  and 

prevent  them  from  striking,  by  their  inertia,  against  the 
sides  of  the  case  and  cracking  it,  when  the  piece  is  fired. 
A  hole  is  bored  through  the  mass  of  sulphur  and  bullets, 
to  receive  the  bursting  charge;  and,  in  order  not  to 
displace  too  many  bullets,  and  not  to  scatter  them  too 
far  when  the  shot  bursts,  the  bursting  charge  should 
only  be  sufficient  to  produce  rupture. 

If  the  iron,  of  which  the  case  is  made,  were  always 
of  suitable  quality,  and  the  cavity  filled  with  bullets 
snugly  packed  in,  there  would  be  no  necessity  for  sul- 
phur to  prevent  accidents.  In  this  case,  it  would  not 
be  necessary  to  remove  any  of  the  bullets,  as  the  burst- 
ing charge  would  be  disseminated  through  the  inter- 
stices ;  and  the  difficulty,  which  now  sometimes  arises 


Ifin^ 

IP- 

BAK-SH0T.  83 

from  their  adhering  to  fragments  of  the  case,  would  be 
entirely  obviated. 

To  increase  the  effect  of  a  small  bursting  charge,  the 
lower  portion  of  the  fuze-hole,  b,  fig.  14,  is  partially 
closed,  by  screwing  into  it  a  disk  perforated  with  a 
small  hole  for  the  passage  of  the  flame  from  the  fuze. 
The  spherical  case-shot  mostly  used  for  field  service  is 
the  12-pounder;  it  contains  about  80  bullets;  its  burst- 
ing charge  is  1  oz.  of  powder ;  and  it  weighs  when  fin- 
ished 11.75  lbs., — nearly  as  much  as  a  solid  shot  of  the 
same  calibre. 

The  rupture  of  a  spherical  case-shot  may  be  made  to 
take  place  at  any  point  of  its  flight ;  and  in  this  re- 
spect it  is  superior  to  canister  and  grape-shot,  which 
begin  to  separate  the  moment  they  leave  the  piece. 

47.  Bar-shot.  Bar-shot  consist  of  two  hemispheres,  or 
two  spheres,  connected  together  by  a  bar  of  iron ;  the 
motion  of  rotation  which  these  projectiles  assume  in 
flight,  renders  them  useful  in  cutting  the  masts  and 
rigging  of  vessels ;  but,  as  they  are  very  inaccurate, 
they  are  only  employed  at  short  distances.  They  are 
very  little  used,  however,  at  the  present  day. 

Chain-shot  only  differ  from  bar-shot  in  the  mode  of 
connection,  which  is  a  chain,  instead  of  a  bar. 

48.  Percussion  bullets.  Percussion  bullets  may  be 
made  by  placing  a  small  quantity  of  percussion  powder, 

enclosed  in  a  copper  envelope,  in  the  point 
of  an  ordinary  rifle-musket  bullet,  or  by 
casting  the  bullet  around  a  small  iron  tube, 
which  is  afterward  filled  with  powder  and 
surmounted  with  a  common  percussion-cap. 
^i^^p5*1    The  impact  of  the  bullet  against  a  sub- 


84  PROJECTILES. RUPTURE. 

stance  no  harder  than  wood  is  found  to  ignite  the 
percussion  charge  or  cap,  and  produce  an  effective 
explosion. 

These  projectiles  can  be  used  to  blow  up  caissons,  and 
boxes  containing  ammunition,  at  very  long  ditsances. 

49.  Carcasses.  Carcasses  are  shells  which  have  three 
additional  holes,  of  the  same  dimensions  as  the  fuze- 
hole,  pierced  at  equal  distances  apart  in  their  upper 
hemispheres,  with  their  exterior  openings  tangent  to 
the  great  circle  perpendicular  to  the  axis  of  the  fuze- 
hole.  The  object  of  a  carcass  is  to  set  fire  to  wooden 
structures,  by  the  flame  of  the  burning  composition 
which  issues  through  the  holes. 

CHARGE  OF  RUPTURE  OF  SHELLS. 

50.  Plane  of  rupture.  Suppose  the  cavity  of  the 
shell  to  be  spherical,  and  concentric  with  the  exterior. 
As  soon  as  the  enclosed  charge  of  powder  is  inflamed, 
the  gases  developed  expand  into  the  cavity,  and  the 
expansive  force  increases  until  it  is  sufficient  to  over- 
come the  tenacity  of  the  metal,  and  produce  rupture ; 
which  will  take  place  in  the  direction  of  least  resistance, 
or  following  a  surface  composed  of  lines  normals  to  the 
two  surfaces. 

Let  R  be  the  radius  of  the  exterior, 
and  r  the  radius  of  the  interior  surface ; 
0,  the  common  centre  of  the  two  spheres ; 
T,  the  tenacity  of  the  material  of  which 
the  sphere  is  composed  ;  and  />,  the  pres- 
Fig.  16.  sure  on  a  unit  0f  surface  to  overcome  the 
tenacity  of  the  metal. 


PLANE    OF    KUPTURE.  85 

Let  C  be  the  radius  of  the  circle  of  rupture  on  the 
interior  surface.  From  the  known  properties  of  gases, 
the  pressure  exercised  on  the  area  of  this  circle  to  pro- 
duce rupture  is  equal  to  the  components  of  all  the  nor- 
mal pressures  acting  on  the  spherical  segment  of  which 
it  is  the  base,  taken  perpendicularly  to  the  plane  of  this 
circle  ;  therefore  npC2  is  the  pressure  of  the  gases  which 
tends  to  break  the  sphere. 

Under  this  supposition,  rupture  should  follow  the 
surface  of  the  frustrum  of  a  cone  of  which  this  circle  is 
the  smaller  base. 

The  surface  of  this  frustrum  is  equal  to  the  differ- 
ence of  the  surfaces  of  two  cones  whose  common  apex 
is  at  the  centre  of  the  sphere.  The  base  of  the  smaller 
is  2  7r  CJ  and  its  slant  height  r ;  its  surface  therefore  is 
equal  to  nCr,  The  surface  of  the  larger  cone,  whose 
generatrix  is  the  radius  of  the  exterior  sphere,  will  be 

R2 

to   the   smaller   as  R2  is  to  r2,  and  therefore  -nCr— 

their  difference,  or  the  area  of  the  surface  of  rupture 


will  be  equal  to 


-«(>-') 


If  the  pressure  of  the  gases  acted  normally  to  the  sur- 
face of  the  fracture,  or  in  the  direction  of  the  tenacity, 
this  surface  multiplied  by  T  would  give  the  total  resist- 
ance, which  should  be  equal  to  the  pressure  of  the 
gases ;  but  it  acts  obliquely,  and  to  produce  rupture 
should  be  increased  by  a  quantity  which  depends  on 
the  law  of  increase  of  the  resistance  due  to  the  angle 
which  the  pressure  makes  with  the  normal.  Although 
we  cannot  measure  this  resistance,  it  must  be  admitted 


86  PROJECTILES. RUPTURE. 

that  the  effect  to  overcome  is  greatest  when  the  power 
is  in  the  direction  of  the  normal  to  the  surface  of 
rupture. 

We  shall,  therefore,  have  the  relation, 


pnC2  =  TnCr(~-l\+d 


y=^)+ 


Or, 


In  this  expression  the  value  of  6  is  unknown ;  but  it 
is  easy  to  be  seen  that  it  diminishes  as  the  direction  of 
the  pressure  approaches  the  normal,  and  when  they 
coincide  6  becomes  0.  At  the  same  time  C  increases, 
and  the  value  of  p  diminishes,  until  C  becomes  equal 
to  r,  its  maximum  value.  Therefore,  the  section  of 
easiest  rupture  of  a  hollow  sphere  passes  through  a 
great  circle,  and  the  pressure  which  is  in  equilibrio  with 
the  tenacity  of  the  metal,  will  be  given  by  the  fore- 
going formula,  by  making  C=  r,  and  (5=0 ;  it  will  then 
become, 

When  the  pressure  is  less  than  this  value  of  J9,  the 
sphere  will  resist  its  charge  of  powder;  when  it  is 
greater  than  this  value,  the  sphere  will  burst. 

The  density  of  the  gaseous  products  of  the  powder 
necessary  to  burst  the  sphere  can  be  easily  found  by 
Rumford's  formula : 


Atmos. 

L  +  0.362d 


p=  1.841  (905d)v 
but  d,  or  the  density  of  the  gaseous  products,  is  equal 


LOSS    OF    GAS.  87 

to  their  weight,  or  the  weight  of  the  bursting  charge, 
divided  by  the  interior  space  of  the  sphere. 


j       w 
Or,  "  **'*' 


51.  Lo§s  of  gas  by  fuze-hole.  This  loss  of  force  by  the 
fuze-hole  may  be  ascertained  with  sufficient  accuracy, 
provided  we  know  from  actual  experiment  the  amount 
of  the  loss  from  the  fuze-hole  of  any  one  shell. 

Let  H  and  r  be  the  exterior  and  interior  radii  of  a 
spherical  projectile ;  T,  the  tenacity  of  the  metal ;  iy  the 
radius  of  the  fuze-hole  ;  ?//,  the  weight  of  powder  neces- 
sary to  burst  it  under  the  supposition  that  there  is  no 
loss  of  force  at  the  fuze-hole  ;  w,  the  weight  of  powder 
that  is  actually  required  to  burst  it.  By  the  preceding 
formulas  we  obtain  the  value  of  w'\  lu—w  is  therefore 
the  amount  of  loss  by  the  fuze-hole.  Take  another  pro- 
jectile, and  let  w\  represent  the  charge  which  is  neces- 
sary to  burst  it,  under  the  supposition  that  there  is  no 
loss,  and  w/  the  weight  that  is  found  by  experiment 
necessary  to  burst  it;  w, — w\  will  represent  the  loss. 
We  are  at  liberty  to  suppose  the  loss  from  the  two 
fuze-holes  is  proportional  to  the  size  of  the  holes,  and 
the  density  of  the  gases  at  the  moment  of  rupture  ;  we 
shall,  therefore,  have  this  proportion, 

w—w'  :  w/—w/  : :  #d :  i*dt 

i  ,  /  ,\#d 

or,  w=w  -\-{w—w.  j-tttt- 

From  the  experiments  made  at  Metz  in  1835,  it  was 
shown  that  this  mode  of  estimating  the  loss  of  force  by 


88  PKOJECTILES. FABRICATION. 

the  fuze-hole,  was  sufficiently  exact  for  practical  pur- 
poses. 

FABRICATION  OF  PROJECTILES. 

52.  Materials.  Shot  and  shells  should  be  made  of 
gray  or  mottled  iron,  of  good  quality. 

Spherical  case-shot  should  be  made  of  the  best  quality 
of  iron,  and  with  peculiar  care,  in  order  that  they  may 
not  break  in  the  gun. 

All  projectiles  should  be  cast  in  sand  and  not  in  iron 
moulds,  as  those  from  the  latter  are  generally  not  spher- 
ical in  form,  nor  uniform  in  size ;  they  are  also  full  of 
cavities,  and  are  cracked  by  being  heated. 

Sand.  The  sand  used  should  be  silicious,  of  an  angu- 
lar grain,  and  moderate  degree  of  fineness.  It  should 
be  mixed  with  a  sufficient  quantity  of  clay,  so  that, 
when  slightly  moistened,  it  will  retain  its  shape  when 
pressed  in  the  hand. 

Pattern.  The  pattern  of  a  spherical  projectile  is  corn- 
Fig.  17.  to  draw  it  from  the  sand  when 
the  half-niould  is  completed.     The  flasks  which  contain 
the  mould  are  made  of  cast  iron,  in  two  equal  parts 
united  at  their  larger  bases. 

Moulding.  This  operation  is  performed  by  placing 
the  flat  side  of  one  of  the  hemispheres  on  the  moulding 
board,    and   covering   it   with  a  flask.     Sand  is  then 


PATTERN.  89 

poured  into  the  flask,  filling  up  the  entire  space  between 
it  and  the  hemisphere,  and  well  rammed.  The  flask  is 
then  turned  over,  the  hemisphere  is  withdrawn,  and  the 
entire  surface  of  the  sand  painted  with  coke-wash,  and 
dried.  The  remaining  half  of  the  mould  is  formed  in 
the  same  way,  except  that  a  channel  for  the  introduc- 
tion of  the  melted  iron  is  made  by  inserting  a  round 
stick  in  the  sand  before  it  is  rammed,  and  withdrawing 
it  afterward. 

This  channel  forms  a  sinking  head,  and  supplies  any 
deficiency  of  metal  in  the  mould.  The  inner  orifice  of 
the  sinking  head  should  be  situated  at  the  side  of  the 
mould,  in  order  that  the  surface  of  the  sand  may  not  be 
broken  by  the  falling  metal. 

Hollow  projectiles.  Thus  far,  the  operation  of  mould- 
ing and  casting  solid  and  hollow  projectiles  are  the 
same.  The  cavity  of  a  hollow  projectile  is  made  by  in- 
serting a  core  of  sand,  which  is  formed  around  a  stem 
fastened  into  the  lower  half  of  the  mould.  The  stem  is 
hollow,  and  perforated  with  small  holes  to  allow  of  the 
escape  of  steam  and  gas  generated  by  the  heat  of  the 
melted  metal.  It  is  also  made  of  iron,  but  that  part  of 
it  which  comes  in  contact  with  the  melted  iron,  and 
forms  the  fuze-hole,  is  coated  with  sand. 

In  pouring  the  melted  iron  into  the  mould  with  the 
ladle,  care  should  be  taken  to  prevent  scoria  and  dirt 
from  entering  with  it ;  and,  for  this  purpose,  the  sur- 
face should  be  skimmed  with  a  wooden  stick. 

Before  the  iron  is  fairly  cooled,  the  flasks  are  open- 
ed, and  the  sand  knocked  from  the  castings.  After  this, 
the  core  is  broken  up  and  knocked  out,  and  the  in- 
terior surface  cleaned  by  a  scraper.     The  sinking  head 


90  PKOJECTILES. INSPECTION. 

and  other  excrescences  are  knocked  off,  and  the  surface 
smoothed  in  a  rolling-barrel,  or  with  a  file,  or  chisel, 
if  necessary.  The  fuze-hole  is  then  reamed  out  to  the 
proper  size,  and  the  projectile  is  ready  for  inspection. 

INSPECTION    OF   PROJECTILES. 

53.  Object  of  inspection.  The  principal  points  to  be 
observed  in  inspecting  shot  and  shells  are,  to  see  that 
they  are  of  proper  size  in  all  their  parts ;  that  they 
are  made  of  suitable  metal;  and  that  they  have  no 
defects,  concealed  or  otherwise,  which  will  endanger 
their  use,  or  impair  the  accuracy  of  their  fire. 

As  it  would  be  impracticable  to  make  all  projectiles 
of  exact  dimensions,  certain  variations  are  allowed  in 
the  fabrication.     See  Ordnance  Manual. 

Inspection  of  shot.  The  instruments  are  one  large 
and  one  small  gauge,  and  one  cylinder  gauge ;  the  cylin- 
der gauge  has  the  same  diameter  as  the  large  gauge,  it 
is  made  of  cast  iron,  and  is  five  calibres  long.  There 
are  also,  one  hammer  with  a  conical  point,  six  steel 
punches,  and  one  searcher  made  of  wire. 

The  shot  should  be  inspected  before  they  become 
rusty  ;  after  being  well  cleaned,  each  shot  is  placed  on 
a  table  and  examined  by  the  eye  to  see  that  its  surface 
is  smooth,  and  that  the  metal  is  sound  and  free  from 
seams,  flaws,  and  blisters.  If  cavities  or  small  holes 
appear  on  the  surface,  strike  the  point  of  the  hammer 
or  punch  into  them,  and  ascertain  their  depth  with  the 
searcher ;  if  the  depth  of  the  cavity  exceed  0.2  inch, 
the  shot  is  rejected ;  and  also  if  it  appear  that  an  at- 
tempt has  been  made  to  conceal  such  defects  by  filling 
them  up  with  nails,  cement,  &c. 


INSPECTION.  91 

The  shot  must  pass  in  every  direction  through  the 
large  gauge,  and  not  at  all  through  the  small  one  ;  the 
founder  should  endeavor  to  bring  the  shot  up  as  near 
as  possible  to  the  large  gauge,  or  to  the  true  diam- 
eter. 

After  having  been  thus  examined,  the  shot  are  pass- 
ed through  the  cylinder  gauge,  which  is  placed  in  an  in- 
clined position,  and  turned  from  time  to  time,  to  pre- 
vent its  being  worn  into  furrows ;  shot  which  slide  or 
stick  in  the  cylinder  are  rejected. 

Shot  are  proved  by  dropping  them  from  a  height  of 
twenty  feet  on  a  block  of  iron,  or  rolling  them  down  an 
inclined  plane  of  that  height,  against  another  shot  at 
the  bottom  of  the  plane. 

The  average  weight  of  the  shot  is  deduced  from  that 
of  three  parcels  of  twenty  to  fifty  each,  taken  indiscrim- 
inately from  the  pile ;  some  of  those  which  appear  to 
be  the  smallest  should  also  be  weighed,  and  they  are 
rejected  if  they  fall  short  of  the  weight  expressed  by 
•their  calibre,  more  than  one  thirty -second  part.  They 
almost  invariably  exceed  that  weight. 

Inspection  of  grape  and  canister  shot.  The  dimen- 
sions are  verified  by  means  of  a  large  and  small  gauge, 
attached  to  the  same  handle.  The  surface  of  the  shot 
should  be  smooth,  and  free  from  seams. 

Inspection  of  hollow  projectiles.  The  inspecting  in- 
struments are  a  large  and  small  gauge  for  each  calibre, 
and  a  cylinder  gauge  for  shells  of  eight  inches  and 
under. 

Calipers  for  measuring  the  thickness  of  shells  at  the 
sides. 

Calipers  to  measure  the  thickness  at  the  bottom. 


92  PROJECTILES. INSPECTION. 

Gauges  to  verify  the  dimensions  of  the  fuze-hole,  and 
the  thickness  of  the  metal  at  the  fuze-hole. 

A  pair  of  hand-bellows ;  a  wooden  plug  to  fit  the 
fuze-hole,  and  bored  through  to  receive  the  nozzle  of 
the  bellows. 

A  hammer;  a  searcher ;  a  cold  chisel ;  steel  punches. 

Inspection.  The  surface  of  the  shell  and  its  exterior 
dimensions,  are  examined  as  in  the  case  of  shot.  The 
shell  is  next  struck  with  the  hammer,  to  judge  by  the 
sound  whether  it  is  free  from  cracks ;  the  position  and 
dimensions  of  the  ears  are  verified ;  the  thickness  of  the 
metal  is  then  measured  at  several  points  on  the  great 
circle  perpendicular  to  the  axis  of  the  fuze-hole.  The 
diameter  of  the  fuze-hole,  which  should  be  accurately 
reamed,  is  then  verified,  and  the  soundness  of  the  metal 
about  the  inside  of  the  hole  is  ascertained  by  inserting 
the  finger. 

The  shell  is  now  placed  on  a  trivet,  in  a  tub  contain- 
ing water  deep  enough  to  cover  it  nearly  to  the  fuze- 
hole  ;  the  bellows  and  plug  are  inserted  into  the  fuze- 
hole,  and  the  air  forced  into  the  shell ;  if  there  be  any 
holes  in  the  shell,  the  air  will  rise  in  bubbles  through 
the  water.  This  test  gives  another  indication  of  the 
soundness  of  the  metal,  as  the  parts  containing  cavities 
will  dry  more  slowly  than  other  parts. 

The  mean  weight  of  shells  is  ascertained  in  the  same 
manner  as  that  of  shot.  Shot  and  shells  rejected  in  the 
inspection,  are  marked  with  an  X  made  with  a  cold 
chisel — on  shot  near  the  gate,  and  on  shells  near  the 
fuze-hole. 


PRESEKVATION. PILING.  93 


PKESERVATION  AND   PILING   OF  BALLS. 

54.  lackering.  Projectiles  should  be  carefully  lack- 
ered as  soon  as  possible  after  they  are  received.  When 
it  is  necessary  to  renew  the  lacker,  the  old  lacker  should 
be  removed  by  rolling  or  scraping  the  balls,  which 
should  never  be  heated  for  that  purpose. 

Piling.  Balls  should  be  piled  according  to  kind  and 
calibre,  under  cover  if  practicable,  in  a  place  where  there 
is  a  free  circulation  of  air ;  to  facilitate  which,  the  piles 
should  be  narrow  if  the  locality  permits ;  the  width  of 
the  bottom  tier  may  be  from  twelve  to  fourteen  balls, 
according  to  the  calibre. 

Prepare  the  ground  for  the  base  of  the  pile  by  rais- 
ing it  above  the  level  of  the  surrounding  ground,  so  as 
to  throw  off  the  water ;  level  it,  ram  it  well,  and  cover 
it  with  a  layer  of  screened  sand.  Make  the  bottom  of 
the  pile  with  a  tier  of  unserviceable  balls,  buried  about 
two-thirds  of  their  diameter  in  the  sand ;  this  base  may 
be  made  permanent ;  clean  the  base  well,  and  form  the 
pile,  putting  the  fuze-holes  of  the  shells  downward,  in 
the  intervals,  and  not  resting  on  the  shells  below. 

The  base  may  be  also  made  of  bricks,  concrete,  stone, 
or  with  borders  and  braces  of  iron. 

55.  To  find  the  number  of  balls  in  a  pile.  Multiply 
the  sura  of  the  three  parallel  edges  by  one-third  of  the 
number  in  a  triangular  face. 

In  a  square  pile,  one  of  the  parallel  edges  contains 
but  one  ball;  in  a  /triangular  pile,  two  of  the  edges 
have  but  one  ball  in  each. 


94  PEOJECTILES. EOCKETS. 

The  number  of  balls  in  a  triangular  face  is     ^   ~*~  , 

n  being  the  number  in  the  bottom  row. 

The  sum  of  the  three  parallel  edges  in  a  triangular 
pile  is  n -\-2  ;  in  a  square  pile,  2n-\-l ;  in  an  oblong  pile, 
3JV-\-2n—2  ;  N  being  the  length  of  the  top  row,  and  n 
the  width  of  the  bottom  tier;  or  3m— n-\-\;  m  being 
the  length,  and  n  the  width  of  the  bottom  tier. 

If  a  pile  consist  of  two  joined  at  right  angles,  calcu- 
late the  contents  of  one  as  a  common  pile,  and  the  other 
as  a  pile  of  which  three  parallel  edges  are  equal. 


THEORY  AND  CONSTRUCTION  OF  ROCKETS. 

56.  structure,  A  rocket  is  a  projectile  which  is  set  in 
motion  by  a  force  residing  withjn  itself;  it  therefore 
performs  the  two-fold  function  of  piece  and  projectile. 

It  is  essentially  composed  of  a  strong  case  of  paper  or 
wrought  iron,  enclosing  a  composition  of  nitre,  charcoal, 
and  sulphur — the  same  as  gunpowder,  except  that  the 
ingredients  are  proportioned  for  a  slower  rate  of  com- 
bustion. If  penetration  and  range  be  required,  its  head 
is  surmounted  by  a  solid  shot  /  if  explosion  and  incen- 
diary effect,  by  a  shell  or  spherical  case-shot,  to  which  is 
attached  a  fuze,  which  is  set  on  fire  when  it  is  reached 
by  the  flame  of  the  burning  composition.  The  base  is 
perforated  by  one  or  more  vents  for  the  escape  of  the  gas 
generated  within,  and  sometimes  with  a  screw-hole  to 
which  a  guide-stick  is  fastened. 

The  disposition  of  the  different  parts  will  be  readily 
understood  by  reference  to  the  subjoined  figure,  which 


MOTION.  95 

represents  a  section  through  the  long  axis  of  a  Congreve 
rocket. 


Fig.  18. 

57.  uiotion.  A  rocket  is  set  in  motion  by  the  reaction 
of  a  rapid  stream  of  gas  escaping  through  its  vents.  If 
it  be  surrounded  by  a  resisting  medium,  the  atmosphere 
for  instance,  the  particles  of  gas,  as  they  issue  from  the 
vent,  will  impinge  against  and  set  in  motion  certain  par- 
ticles of  air,  and  the  force  expended  on  the  inertia  of 
these  particles  will  react  and  increase  the  propelling 
force  of  the  rocket.  It  follows,  therefore,  that,  though 
a  rocket  will  move  in  vacuo,  its  propelling  force  will 
be  increased  by  the  presence  of  a  resisting  medium. 
Whether  the  effect  will  be  to  accelerate  the  rocket  de- 
pends upon  the  relation  between  the  resistance  which 
the  medium  offers  to  the  motion  of  the  gas,  and  that 
which  it  offers  to  the  motion  of  the  rocket. 

Vent.  As  the  rate  of  combustion  of  the  composition 
is  independent  of  the  pressure  of  the  gas  in  the  bore,  it 
follows,  that  if  the  size  of  the  vent  be  contracted,  the 
flow  of  gas  through  it  will  be  accelerated.  The  strength 
of  the  case,  and  the  friction  of  the  gas,  which  increases  as 
the  vent  diminishes,  alone  limit  the  reduction  of  the 
size  of  the  vent. 

For  vents  of  the  same  size,  but  of  different  shapes, 
that  one  which  allows  the  gas  to  escape  most  freely, 
will  be  most  favorable  to  the  flight  of  the  rocket.  A 
conical  form  of  vent,  with  the  larger  orifice  next  to  the 
bore,  will  allow  the  gas  to  escape  more  rapidly  than 


96  PROJECTILES. ROCKETS. 

one  of  cylindrical  form.  This  may  be  shown  by  burn- 
ing portfire  composition  in  tubes  with  different-shaped 
vents.  It  will  be  found  that  the  sparks  from  a  conical 
vent  will  be  thrown  much  higher  than  those  from  a 
cylindrical  vent ;  the  relative  heights  depending  on  the 
slope  of  the  sides  of  the  conical  vent. 

Bwe.  As  the  composition  of  a  rocket  burns  in 
parallel  layers  of  uniform  thickness,  the  amount  of  gas 
generated  in  a  given  time,  or  the  velocity  of  its  exit 
from  the  case,  depends  on  the  extent  of  the  inflamed 
surface. 

Experience  shows  that  to  obtain  the  required  sur- 
face of  inflammation,  it  is  necessary  to  form  a  long 
cavity  in  the  mass  of  the  composition.  This  cavity  is 
called  the  lore.  In  small  rockets,  the  bore  is  formed  by 
driving  the  composition  around  a  spindle  which  is  after- 
ward withdrawn  ;  but  in  the  large  ones,  the  composition 
is  driven  into  the  case  in  a  solid  mass  by  a  powerful 
hydrostatic  press,  and  then  bored  out  with  a  bit.  In 
all  rockets  the  bore  should  be  concentric  with  the  case  ; 
its  shape  should  be  made  conical  to  facilitate  the  draw- 
ing out  of  the  spindle,  and  to  diminish  the  strain  on  the 
case  near  its  head,  by  reducing  the  amount  of  surface 
where  the  pressure  on  the  unit  of  surface  is  greatest. 

Nature  of  movement  Suppose  the  rocket  in  a  state 
of  rest,  and  the  composition  ignited;  the  flame  imme- 
diately spreads  over  the  surface  of  the  bore,  forming 
gas,  which  issues  from  the  vent.  The  escape  is  slow  in 
the  first  moments,  as  the  density  of  the  gas  is  slight ; 
but  as  the  surface  of  the  inflammation  is  large  compared 
to  the  size  of  the  vent,  the  gas  accumulates  rapidly,  and 
its  density  is  increased  until  the  velocity  of  the  escape 


GUIDING    PRINCIPLE.  97 

is  sufficient  to  overcome  the  resistances  which  the 
rocket  offers  to  motion.  These  resistances  are,  inertia, 
friction,  the  component  of  weight  in  the  direction  of 
motion,  and,  after  motion  takes  place,  the  resistance  of 
the  air. 

The  constant  pressure  on  the  head  of  the  bore  accel- 
erates the  motion  of  the  rocket  until  the  resistance  of 
the  air  equals  the  propelling  force ;  after  this,  it  will 
remain  constant  until  the  burning  surface  is  sensibly 
diminished.  When  the  gas  ceases  to  flow,  the  rocket 
loses  its  distinctive  character,  and  becomes,  so  far  as  its 
movement  is  concerned,  an  ordinary  projectile. 

The  increase  in  the  surface  of  combustion  whereby 
more  gas  is  developed  in  the  same  time,  and  the  dimi- 
nution in  the  weight  of  the  remaining  composition, 
cause  the  point  of  maximum  velocity  to  be  reached 
with  increased  rapidity..  If  the  weight  of  the  rocket  be 
increased,  the  instant  of  maximum  velocity  will  be  pro- 
longed, but  the  amount  will  remain  the  same.  A  change 
in  the  form  of  the  rocket  which  increases  the  resistance 
of  the  air,  will  have  the  effect  to  diminish  the  maximum 
velocity. 

The  maximum  velocity  of  French  rockets,  and  the 
distances  at  which  they  are  attained,  are  given  in  the 
following  table : — 

CALIBRE.  DISTANCE.  MAXM.  VELOCITY. 

2}  inches,  134  yds.  278  yds. 

3£      "  141    "  370     " 

According  to*  the-  calculations  of  Piobert,  for  small 
rockets  it  takes  about  f-  second  for  the  gas  to  attain  its 
maximum  velocity  of  850  yds. 

58.  Ouiding  principle.     The   propelling  force   of  a 

7 


98  PEOJECTILES. KOCKETS. 

rocket  changes  its  direction  with  the  axis  along  which 
it  acts ;  it  follows,  therefore,  that  without  some  means 
of  giving  stability  to  this  axis,  the  path  described  will 
be  very  irregular,  so  much  so,  at  times,  as  to  fold  upon 
itself;  and  instances  have  been  known  where  these  pro- 
jectiles have  returned  to  the  point  whence  they  started. 

An  example  of  this  irregular  motion  may  be  seen  in 
"serpents,"  a  species  of  small  rockets  without  guide- 
sticks. 

The  two  means  now  used  to  give  steadiness  to  the 
flight  of  a  rocket  are,  rotation,  as  in  the  case  of  a  rifle- 
ball,  and  the  resistance  of  the  air,  as  in  an  arrow. 

Holds  system.  The  first  is  exemplified  in  Hale's 
rocket,  where  rotation  is  produced  around  the  long  axis 
by  the  escape  of  the  gas  through  five  small  vents  situ- 
ated obliquely  to  it.  In  his  first  arrangement,  the  in- 
ventor placed  the  small  vents  in  the  base,  surrounding 
the  large  central  vent,  so  that  the  resultant  of  the  tan- 
gential forces  acted  around  the  posterior  extremity  of 
the  axis  of  rotation.  In  1855,  this  arrangement  was 
changed  by  reducing  the  number  of  the  small  vents  to 
three,  and  placing  them  at  the  base  of  the  head  of  the 
rocket.  The  rocket  thus  modified,  and  shown  in  fig.  20, 
is  the  one  now  used  by  the  United  States  government  for 
war  purposes  * 

*  It  is  said  that  Mr.  Hale's  latest  improvement  consists  in  placing  the  tan- 
gential vents  in  a  plane  passing  through  the  centre  of  gravity  of  the  rocket, 

and   at    right    angles    to    the 

axis.       This    is    accomplished 

by  dividing  the  case  into  two 

distinct  parts,   or   rockets,  by 

-pjg    19  a  perforated    partition.      The 

composition  in  the  front  part 

furnishes  the  gas  for  rotation,  and  that  in  the  rear  the  gas  for  propulsion.    See 

fig  19. — New  Resources  of  Warfare,  by  Scoff  em. 


HOW    FIKED. 


99 


Fig.  20. 
a.  .Bore  and  vent. 
b . .  Recess  in  the  base  of  the  head. 


c.  .Tangential  vent  (three). 

d.  .Head  (solid). 


Congrevds  system.  A  Congreve  rocket  is  guided  by 
a  long  wooden  stick  attached  to  its  base.  If  any  cause 
act  to  turn  it  from  its  proper  direction,  it  will  be  op- 
posed by  resistances  equal  to  its  moment  of  inertia  and 
the  lateral  action  of  the  air  against  the  stick. 

The  effect  of  these  resistances  wrill  be  increased  by 
placing  the  centre  of  gravity  near  the  head  of  the 
rocket,  and  by  increasing  the  surface  of  the  stick. 

In  signal  rockets,  where  the  case  is  made  of  paper, 
the  stick  is  attached  to  the  side  by  wrapping  around 
twine;  and  there  is  but  one  large  vent,  which  is  in  the 
centre  of  the  case. 

In  war-rockets  the  stick  is  attached  to  the  centre  of 
the  base,  and  the  large  central  vent  is  replaced  by 
several  small  ones  near  its  circumference.  See  fig.  18. 
The  former  arrangement  is  not  so  favorable  to  accuracy 
as  the  latt3r,  inasmuch  as  rotation  will  be  produced  if 
the  force  of  propulsion  and  the  resistance  of  the  air  do 
not  act  in  the  same  line. 

59.  How  fired.  Rockets  are  generally  fired  from  tubes 
or  gutters ;  but  should  occasion  require  it,  they  may  be 
fired  directly  from  the  ground,  care  being  taken  to 
raise  the  forward  end  by  propping  it  up  with  a  stick  or 
stone.  As  the  motion  is  slow  in  the  first  moments  of 
its  flight,   it  is  more  liable   to  be    deviated  from   its 


100  PROJECTILES. ROCKETS. 

proper  direction  at  this  time  than  any  other ;  for  this 
reason  the  conducting  tube  should  be  as  long  as  prac- 
ticable, say  from  five  to  ten  feet.* 

60.  Form  of  trajectory.  Take  that  portion  of  the 
trajectory  where  the  velocity  is  uniform.  The  weight 
of  the  rocket  applied  at  its  centre  of  gravity,  and  acting 
in  a  vertical  direction,  and  the  propelling  force  acting  in 
the  direction  of  its  length,  are  two  forces  the  oblique 
resultant  of  which  moves  the  rocket  parallel  to  itself; 
but  the  resistance  of  the  air  is  oblique  to  this  direction, 
and  acting  at  the  centre  of  figure,  a  point  situated  be- 
tween the  centre  of  gravity  and  extremity  of  the  guide- 
stick,  produces  a  rotation  which  raises  the  stick,  and 
thereby  changes  the  direction  in  which  the  gas  acts. 
As  these  forces  are  constantly  acting,  it  follows  that 
each  element  of  the  trajectory  has  less  inclination  to 
the  horizon  than  the  element  of  an  ordinary  trajectory 
in  which  the  velocity  is  equal. 

When  the  velocity  is  not  uniform,  the  position  of 
the  centre  of  gravity  has  a  certain  influence  on  the  form 
of  the  trajectory.  To  understand  this,  it  is  necessary  to 
consider  that  the  component  of  the  resistance  of  the 
air  which  acts  on  the  head  of  the  rocket  is  greater  than 
that  which  acts  on  the  side  of  the  stick.  It  is  also  ne- 
cessary to  consider  that  the  pressure  of  the  inflamed 
gas  acts  in  a  direction  opposite  to  the  resistance  of  the 
air,  that  is  to  say,  from  the  rear  to  the  front,  and  that 
the  centre  of  gravity  is  near  the  rear  extremity  of  the 
case. 


*  Mr.  Hale  has  suggested  a  means  of  using  a  short  tube,  by  applying  a  pressure 
to  the  rfccket  to  retain  it  in  its  place  until  the^  gas  has  acquired  the  requisite 
velocity. 


TOEM    OF    TRAJECTORY.  101 

At  the  beginning  of  the  trajectory,  when  the  motion 
of  the  rocket  is  accelerated,  its  inertia  is  opposed  to 
motion,  and  being  applied  at  the  centre  of  gravity, 
which  is  in  rear  of  the  vent,  the  point  of  application 
of  the  moving  force,  it  acts  to  prevent  the  rocket  from 
turning  over  in  its  flight.  But  when  the  composition 
is  consumed,  the  centre  of  gravity  is  thrown  further  to 
the  rear,  and  the  velocity  of  the  rocket  is  retarded,  the 
inertia  acts  in  the  opposite  direction,  and  the  effect  will 
be,  if  the  centre  of  gravity  or  inertia  is  sufficiently  far 
to  the  rear,  to  cause  it  to  turn  over  in  the  direction  of 
its  length. 

If  the  rocket  be  directed  toward  the  earth,  this 
turning  over  will  be  counteracted  by  the  acceleration 
of  velocity  due  to  the  weight,  and  the  form  of  the 
trajectory  will  be  preserved. 

Effect  of  wind.  When  the  wind  acts  obliquely  to 
the  plane  of  fire,  its  component  perpendicular  to  this 
plane,  acting  at  the  centre  of  figure,  will  cause  the 
rocket  to  rotate  around  its  centre  of  gravity.  As  the 
centre  of  figure  is  situated  in  rear  of  the  centre  of  grav- 
ity, the  point  will  be  thrown  toward  the  wind,  and  the 
propelling  force  acting  always  in  the  direction  of  the 
axis,  the  rocket  will  be  urged  toward  the  direction  of 
the  wind.  To  make  an  allowance  for  the  wind,  in 
firing  rockets,  they  should  be  pointed  toward  the  op- 
posite side  from  which  the  wind  comes,  or  with  the 
wind  instead  of  against  it. 

If  the  wind  act  in  the  plane  of  fire  from  front  to 
rear,  it  will  have  the  effect  to  depress  the  point,  and 
with  it  the  elements  of  the  trajectory  in  the  ascending 
branch,  and  elevate  them  in  the  descending  branch ;  as 


102  PEO  JECTILES. ROCKETS. 

the  latter  is  shorter  than  the  former,  the  effect  of  a 
front  wind  will  be  to  diminish  the  range.  The  converse 
will  be  true  for  a  rear  wind. 

61.  History.  Rockets  were  used  in  India  and  China 
for  war  purposes  before  the  discovery  of  gunpowder; 
some  writers  fix  the  date  of  their  invention  about  the 
close  of  the  ninth  century.  Their  inferior  force  and  ac- 
curacy limited  the  sphere  of  their  operations  to  incen- 
diary purposes,  until  the  year  1804,  when  v  Sir  William 
Congreve  turned  his  attention  to  their  improvement. 
This  officer  substituted  sheet-iron  cases  for  those  made 
of  paper,  which  enabled  him  to  use  a  more  powerful 
composition ;  he  made  the  guide-stick  shorter  and 
lighter,  and  removed  a  source  of  inaccuracy  of  flight  by 
attaching  the  stick  to  the  centre  of  the  base  instead  of 
the  side  of  the  case.  He  states  that  he  was  enabled  by 
his  improvements  to  increase  the  range  of  6-pdr.  rock- 
ets from  600  to  2,000  yards.  Under  his  direction  they 
were  prepared,  and  used  successfully  at  the  siege  of 
Boulogne  and  the  battle  of  Leipsic.  At  the  latter 
place  they  were  served  by  a  special  corps. 

62.  Advantages.  The  advantages  claimed  for  rockets 
over  cannon  are,  unlimited  size  of  projectile ;  portabil- 
ity; freedom  from  recoil;  rapidity  of  discharge;  and 
the  terror  which  their  noise  and  fiery  trail  produce  on 
mounted  troops. 

The  numerous  conditions  to  be  fulfilled  in  their  con- 
struction in  order  to  obtain  accuracy  of  flight,  and  the 
uncertainty  of  preserving  the  composition  uninjured  for 
a  length  of  time,  are  difficulties  not  yet  entirely  over- 
come, and  which  have  much  restricted  their  usefulness 
for  general  military  purposes. 


KIND    USED.  103 

63.  Kind  used.  The  two  sizes  of  Hale's  rockets  in 
use  in  the  American  service  are,  the 

2-inch  (interior  diameter  of  case),  weighing  6  lbs. ;  and 
3-inch         "  "  "  "       16  lbs. 

Under  an  angle  of  from  4°  to  5°  the  range  of  these 
rockets  is  from  500  to  600  yds.  Under  an  angle  of  47° 
the  range  of  the  former  is  1,760  yds.  and  the  latter 
2,200. 


O 


104 


CANNON. 


d%(  <^- 


1 


CHAPTER  III. 


HISTORY  OF   CANNON. 


MORTAR. 


64.  The  terms  cannon  and  ordnance  are  applied  to  all 
heavy  fire-arms  which  are  discharged  from  carriages,  in 
contradistinction  to  email  arms,  which  are  discharged 
from  the  hand. 

65.  Early  cannon.*  The 
shape  of  the  first  cannon  used, 
after  the  invention  of  gunpow- 
der was  conical,  internally 
and  externally  resembling  an 
apothecary's  mortar.  They 
Fis-  21.  were  called  mortars,  bombards 

and  vases, 


BOMBARD. 


were  fired  at  high  angles ;  and,  in  conse- 
quence of  the  slow 
burning  of  the  pow- 
der of  that  day,  and 
the  conical  shape  of 
the  bore,  the  stone 
balls  which  they  pro- 
Fig.  22.  jected  moved  with 
very  little  velocity  and  accuracy. 

Perriere.  To  economize  the  action  of  the  powder,  and 
give  a  more  accurate  direction  to  the  projectile,  the  in- 
terior space,  or  bore,  was  afterward  made  nearly  cylin- 
drical, from  4  to  8  calibres  long ;  it  was  terminated  at 

*  Vide  Thiroux. 


ANCIENT    CANNON. 


105 


the  bottom  by  a  very  narrow  and  deep  chamber,  the 
object  of  which  was  to  increase  the  effect  of  the  powder, 
by  retarding  the  escape  of  the  gas  before  it  acted  on 
the  projectile.  These  cannon  were  further  improved  by 
making  the  bores  perfectly  cylindrical ;  and  were  called 
perrieres  (fig.  23),  from  the  fact  that  they  fired  stone 
balls.  They  were  principally  employed  to  breach  stone 
walls,  and  for  this  purpose  were  fired  horizontally. 


PERRIERE. 


Fig.  23. 

66.  Con§truction  of  early  cannon.  The  first  bom- 
bards were  made  of  bars  of  iron,  bound  together  by 
hoops,  after  the  manner  of  the  staves  of  a  barrel.  Fig. 
22.  Afterward  they  were  made  of  wrought  iron,  and 
finally  of  cast  metal.  Bronze  guns  were  used  in  the 
time  of  King  John  of  France. 

Among  the  earliest  cannon  are  found  those  which 
were  loaded  at  the  breech  instead  of  the  muzzle.  One 
of  the  methods  is  shown  in  Hg.  24,  in  which  A  repre- 
sents a  rectangular  opening  formed  at  the  breech  for  the 
purpose  of  receiving  a  movable  chamber,  C9  which  con- 
tained the  charge,  and  was  held  in  its  place  by  a  key, 


Fig    24. 


D.     Though  these  pieces  possessed  great  facility  in  load- 


106 


CANNON. ANCIENT    GUNS. 


ing,  they  were  abandoned  for  want  of  strength  and 
solidity. 

67.  Ancient  guns.  The  introduction  of  cast-iron  pro- 
jectiles, which  are  much  stronger  and  denser  than  those 
of  stone,  led  to  the  invention  of  a  new  species  of  can- 
non, called  cuherins,  which  very  nearly  correspond  in 
construction  and  appearance  to  the  guns  of  the  present 
day.  The  great  strength  of  these  pieces  and  their  pro- 
jectiles, permitted  the  use  of  a  large  charge  of  powder ; 
and  their  introduction  proved  an  important  step  in  the 
improvement  of  artillery. 


CULVERIN. 


OSSii 


•2* 


Pig.  25. 

The  idea  was  entertained  by  ancient  artillerists — 
founded  on  the  relation  which  cannon  were  erroneously 
supposed  to  bear  to  small  arms — that  the  range  increased 
with  the  length  of  the  piece ;  and  in  consequence,  many 
culverins  were  made  of  enormous  length.  A  remark- 
able piece  of  this  description  still  exists  at  Dover,  Eng- 
land, familiarly  known  as  Queen  Anne's  pocket-piece. 
While  it  carries  a  ball  weighing  only  18  lbs.,  it  is  more 
than  25  feet  long. 

68.  Ancient  mortars.  From  the  earliest  days  of  ar- 
tillery there  existed  short,  chambered  pieces,  which 
projected  stone  balls  under  great  angles  of  elevation. 
In  1478,  an  attempt  was  made  to  use  in  these  pieces, 
hollow  projectiles  filled  with  powder,  to  which  was  at- 
tached a  burning  match  to  set  the  powder  on  fire ;  but 
it   is  probable  that  the  accidents  which   accompanied 


CALIBKE. 


107 


their  use  caused  them  to  be  abandoned  for  the  time. 
In  1634,  however,  means  were  devised  to  overcome  this 
difficulty;  and,  thus  perfected,  these  pieces  were  intro- 
duced into  the  French  service  as  a  class  of  cannon  now 
known  as  mortars. 

In  the  reign  of  Louis  XIV.,  a  great  variety  of  mor- 
tars were  used ;  and  some  of  them,  called  Comminges, 
after  their  inventor,  threw  bombs  weighing  550  lbs. 

69.  Ancient  howitzers.  Early  attempts  were  also 
made  to  throw  hollow  projectiles  from  "  perrieres,"  and 
"  culverins,"  or  guns ;  but  great  difficulties  were  expe- 
rienced in  loading  them ;  and  the  accidents  to  which 
they  were  liable,  as  in  the  case  of  mortars,  caused  them 
to  be  abandoned.  Subsequently,  however,  the  Dutch 
artillerists  conceived  the  idea  of  reducing  their  length, 
so  that  the  projectile  could  be  inserted  in  its  place  by 
hand;  and,  thus  improved,  these  cannon  rapidly  came 
into  use,  under  the  name  of  howitzers,  from  the  Ger- 
man, Haubitz. 

70.  Calibre.  The  calibre  of  a  cannon  is  the  diameter 
of  its  bore  expressed  in  inches,  or  the  weight  of  the 
shot  corresponding  to  it.*  Each  nation  early  adopted 
a  series  of  calibres,  decreasing  in  a  geometrical  pro- 
gression. The  principal  series  were  the  French,  or 
32-pounder,    16-pounder,    8-pounder,    4-pounder,    and 

*  In  some  services  the  calibre  refers  to  the  size  of  the  bore,  in  others,  to  the 
size  of  the  shot.     In  Germany,  the  projectile  referred  to  is  a  stone  ball. 

TABLE    OP   CALIBRES    IN  AMERICAN  SERVICE. 


6-pd. 

9-pd. 

12-pd. 

18-pd. 

24-pd. 

32-pd. 

42-pd. 

3.67" 

4.2" 

4.62" 

5.2" 

5.82" 

6.4" 

7.0" 

108  CANNON.  -  "MATERIEL.  SYSTEM. 

2-pounder;  and  the  German,  or  48-pounder,  24-pounder, 
1 2-pounder,  6-pounder,  3-pounder,  and  Impounder. 

71.  Devices.  Down  to  the  time  of  the  French  revo- 
lution, bronze  cannon  were  highly  ornamented  with 
carved  figures  representing  some  fanciful  design,  to- 
gether with  the  national  coat-of-arms  and  cypher  of  the 
reigning  monarch.  Each  piece  also  bore  a  particular 
name  borrowed  from  some  animal  or  passion ;  and 
French  cannon  of  the  ,time  of  Louis  XVI.  bore  the  mot- 
toes,  "  Nee  pluribus  impar,"  and  "  Ultima  ratio  regum." 
That  this  custom  of  naming  cannon  is  not  entirely  ob- 
solete, is  shown  by  a  piece  of  singular  shape  and  con- 
struction, captured  in  the  late  war  with  Mexico,  which 
bears  the  title  of  "El  Terror  del  Norte  Americano." 

72.  " Hateriei."— System.  The  expression,  "materiel 
of  artillery"  embraces  all  cannon,  carriages,  implements, 
ammunition,  &c,  necessary  for  artillery  purposes,  and 
is  used  in  contradistinction  to  "personnel  of  artillery" 
which  refers  to  the  officers  and  men.  The  expression, 
"  system  of  artillery"  refers  to  the  character  and  arrange- 
ment of  the  materiel  of  artillery,  as  adopted  by  a  nation 
at  any  particular  epoch. 

In  the  United  States'  service,  the  term  "  ordnance  and 
ordnance  stores,"  embraces  not  only  all  the  materiel  of 
artillery,  but  the  swords,  small  arms,  and  accoutrements 
used  by  infantry  and  mounted  troops. 

The  principal  qualities  to  be  observed  in  establishing 
a  system  of  artillery  are  simplicity,  mobility,  and  power  ; 
and  the  improvements  which  have  been  made  in  artil- 
lery in  the  last  four  hundred  years  have  had  these  quali- 
ties steadily  in  view. 

The  American  systems  of  field  and  siege  artillery  are 


FIRST   SYSTEM.  109 

chiefly  derived  from  those  of  France ;  it  will,  therefore, 
be  useful  to  the  pupil  to  study  the  history  of  the  latter, 
and  compare  the  successive  steps  of  improvement  which 
have  brought  them  to  their  present  state  of  perfection  * 

73.  First  system.  Toward  the  middle  of  the  sixteenth 
century,  the  various  guns  of  the  French  artillery  were 
reduced  to  six.  The  weights  of  the  balls  correspond- 
ing to  these  calibres  were  33|,  15|,  7|,  2£,  1^,  and  f-  lb. 
respectively.  This  range  of  calibres  was  thought  to  be 
necessary,  for  the  reason  that  it  required  guns  of  large 
calibre  to  destroy  resisting  objects,  while  guns  of  small 
calibre  were  necessary  to  keep  up  with  the  movement 
of  troops. 

Each  of  the  five  principal  calibres  was  mounted  on  a 
different  carriage,  and  the  ammunition,  stores,  and  tools 
were  carried  on  different  store-carts. 

Three  kinds  of  powder  were  used,  viz. :  large-grain, 
small-grain,  and  priming,  which  were  carried  in  barrels 
of  three  sizes. 

The  axle-trees,  which  were  of  wood,  varied  for  the 
different  wheels,  as  well  as  for  the  different  guns.  The 
gun-carriages  were  without  limbers,  and  had  only  two 
wheels,  the  shafts  being  attached  to  the  trails,  which 
often  dragged  along  the  ground.  No  spare  wheels  were 
used,  except  for  pieces  of  large  calibre ;  and  for  facility 
of  transportation  these  were  put  on  an  axle-tree,  so  as  to 
form  a  carriage. 

With  the  exception  of  replacing  injured  wheels,  all 
repairs  were  made  on  the  spot,  from  the  resources  of  the 
country,  and  no  spare  articles  were  carried  with  the 
train.     There  was  no  established  charge  of  powder  for 

*  Vide  New  System  of  Field  Artillery,  by  Captain  Fave. 


110  CANNON. DIFFERENT   SYSTEMS. 

the  guns ;  although  a  weight  equal  to  that  of  the  shot 
was  generally  used. 

Such  was  the  character  of  the  artillery  which  accom- 
panied the  French  armies  up  to  the  middle  of  the  seven- 
teenth century. 

74.  Second  system.  In  the  reign  of  Louis  XIV.,  the 
calibres  of  cannon  were  gradually  changed  by  the  in- 
troduction of  several  foreign  pieces.  There  were  48, 
32,  24,  16,  12,  8,  and  4  pdrs. ;  and  those  of  the  same 
calibre  varied  in  weight,  length,  and  shape. 

Uniformity  existed  in  general  in  each  district  com- 
manded by  a  lieutenant-general  of  artillery,  but  the 
cannon  of  one  district  differed  from  another.  Each 
district  had  (for  the  six  kinds  of  cannon)  six  carriages, 
with  different  wheels,  and  three  kinds  of  limbers,  with 
different  wheels,  making  nine  patterns  of  wheels,  with- 
out counting  those  for  the  platform  wagons  used  to 
transport  heavy  guns,  the  ammunition  carts,  the  trucks, 
and  the  wagons  for  small  stores  and  tools. 

Spare  carriages  were  carried  into  the  field,  but  those 
of  one  district  would  not  fit  the  guns  of  another.  There 
was  but  one  kind  of  powder,  and  this  was  carried  in 
barrels.  The  charge  was  usually  two-thirds  the  weight 
of  the  projectile,  roughly  measured.  Besides  this,  the 
powder  often  varied  in  strength  according  to  the  dis- 
trict from  which  it  came. 

75.  Vaiiere's  system.  In  1732,  General  Valiere  abol- 
ished the  32-pdr.,  as  being  heavy  and  useless,  and  gave  uni- 
formity to  the  five  remaining  calibres.  Toward  the  end 
of  the  18th  century,  mortars,  or  Dutch  howitzers,  were 
sometimes  attached  to  the  field  trains ;  for  the  latter,  a 
small  charge,  and  calibre  of  8  inches,  were  adopted. 


gribeatjval's  system.  Ill 

There  were  also  light  4-pdr.  guns  attached  to  each  regi- 
ment. Up  to  that  time  an  army  always  carried  with 
it  heavy  guns  (24-pdrs.),  and  light  guns  (4-pdrs.),  which 
were  combined  in  the  same  park. 

Valiere  established  a  system  of  uniformity  for  cannon 
throughout  France ;  but  such  was  not  the  case  with  the 
carriages  and  wagons  used  with  them.  Great  exactness 
was  not  then  sought  for,  and  there  existed  as  many 
plans  for  constructing  gun-carriages  as  there  were  ar- 
senals of  construction.  The  axle-trees  were  made  of 
wood,  the  limbers  were  very  low,  and  the  horses  were 
attached  in  single  file. 

75.  Gribcauvai's  sy§tem.  In  1765,  General  Gribeauval 
founded  a  new  system,  by  separating  the  field  from  the 
siege  artillery.  He  diminished  the  charge  of  field-guns 
from  a  half  to  a  third  the  weight  of  the  shot,  but  as  he 
diminished  the  windage  of  the  projectile  at  the  same 
time,  he  was  enabled  to  shorten  them  and  render  them 
lighter,  without  sensibly  diminishing  their  range. 

Field  artillery  then  consisted  of  12,  8,  and  4  pdr. 
guns,  to  which  was  added  a  6-inch  howitzer,  still  retain- 
ing a  small  charge,  but  larger  in  proportion  than  that 
before  used.  For  draught,  the  horses  were  disposed  in 
double  files,  which  was  much  more  favorable  to  rapid 
gaits.  Iron  axle-trees,  higher  limbers,  and  travelling 
trunnion-holes,  rendered  the  draught  easier.  The 
adoption  of  cartridges,  elevating  screws,  and  tangent 
scales,  increased  the  rapidity  and  regularity  of  the  fire. 
Stronger  carriages  were  made  for  the  lighter  guns,  and 
the  different  parts  of  all  were  made  with  more  care,  and 
strengthened  with  iron  work.  Uniformity  was  estab- 
lished in  all  the  new  constructions,  by  compelling  all 


112  CANNON. DIFFERENT    SYSTEMS. 

the  arsenals  to  make  every  part  of  the  carriages,  wagons, 
and  limbers  according  to  certain  fixed  dimensions.  By 
this  exact  correspondence  of  all  the  parts  of  a  carriage, 
spare  parts  could  be  carried  into  the  field  ready  made, 
to  refit.  Thus  an  equipment  was  obtained  which  could 
be  easily  repaired,  and  could  be  moved  with  a  facility 
hitherto  unknown. 

In  order  to  reduce  the  number  of  spare  articles  neces- 
sary for  repairs,  Gribeauval  gave,  as  far  as  practicable, 
the  same  dimensions  to  those  things  which  were  of  the 
same  nature. 

The  excellence  of  this  system  was  tested  in  the  wars 
of  the  French  Republic  and  Empire,  in  which  it  played 
an  important  part. 

77.  stock  trail  §y§tem.  In  1827,  the  system  of  Gri- 
beauval was  changed  by  introducing  the  24  and  32  pdr. 
howitzers,  lengthened  to  correspond  with  the  8  and  12 
pdr.  guns,  and  abolishing  the  4-pdr.  gun  and  6-inch 
howitzer.  Afterward  some  important  improvements 
were  made  in  the  carriages,  chiefly  copied  from  the 
English  system ;  the  number  for  all  field  cannon  was 
reduced  to  two,  the  wheels  of  the  carriage  and  limber 
were  made  of  the  same  size ;  the  weight  of  the  limber 
was  reduced,  and  an  ammunition  chest  placed  on  it ;  the 
method  of  connecting  the  carriage  and  limber  was  sim- 
plified, and  the  operations  of  limbering  and  unlimbering 
greatly  facilitated ;  and  the  two  flasks  which  formed  the 
trail  were  replaced  by  a  single  piece,  called  the  stock, 
which  arrangement  allowed  the  new  pieces  to  turn  in  a 
smaller  space  than  that  required  by  the  old  ones. 

78.  JLouis  Napoleon's  system.  In  1850,  the  present 
Emperor  of  the  French  caused  a  series  of  experiments  to 


RECENT    IMPROVEMENTS.  113 

be  made,  at  the  principal  artillery  schools  of  France,  to 
test  the  merits  of  a  new  system  of  field  artillery  pro- 
posed by  himself.  The  principal  idea  involved  in  this 
system  was,  to  substitute  a  single  gun  of  medium  weight 
and  calibre,  capable  of  firing  shot  and  shells,  for  the  8 
and  12  pdr.  guns  and  24  and  32  pdr.  howitzers,  then  in 
use.     The  calibre  selected  was  the  12  pdr. 

The  favorable  results  of  all  these  experiments,  and 
the  simplicity  of  the  system,  led  to  the  adoption  of  this, 
the  Napoleon  gun,  as  it  is  sometimes  called,  into  the 
French  service ;  and  others  of  similar  principle  were  in- 
troduced into  various  European  services,  and  also  into 
our  own.  As  this  piece  unites  the  properties  of  gun 
and  howitzer,  it  is  called  canon-obusier,  or  gun-howitzer. 

79.  Recent  improvement*.  At  no  time  since  the  dis- 
covery of  gunpowder,  have  such  important  improve- 
ments been  made  in  fire-arms,  as  within  the  past  few 
years.  These  improvements  may  be  summed  up  as  fol- 
lows, viz. : — 

1st.  Improvement  in  the  quality  of  cast  iron,  and  the 
consequent  increase  in  the  calibre  of  sea-coast  cannon. 
In  1820,  the  heaviest  gun  mounted  on  our  sea-coast  bat- 
teries, was  the  24-pdr. ;  at  present,  the  heaviest  is  a 
15-inch  gun,  carrying  a  shell  weighing  420  lbs.  with  50 
lbs.  of  powder.  2d.  The  use  of  wrought  iron  as  a  ma- 
terial for  fortress  carriages,  and  for  covering  ships  of  war. 
3d.  The  extensive  introduction  of  shells  in  sea-coast  de- 
fences and  naval  warfare ;  and  spherical  case-shot  into 
the  field-service ;  and,  4th.  The  successful  application  of 
the  rifle  principle  to  small  arms  and  cannon. 
8 


114  CANNON. CONSTRUCTION. 

CONSTRUCTION,  Ac,  OF  CANNON. 

80.  Definition.  A  cannon  is  a  heavy  machine, 
used  to  set  projectiles  in  motion  by  means  of  gunpowder. 
Its  general  form  is  that  of  a  tube  closed  at  one  end. 

81.  Clas§iflcation.  All  cannon  may  be  classified, 
according  to  their  nature,  as  guns,  howitzers,  and  mor- 
tars ;  and,  according  to  the  uses  to  which  they  are 
applied,  as  field,  mountain,  prairie,  siege,  and  sea-coast 
cannon.  The  recent  introduction  of  rifle-cannon  into 
the  military  service,  requires  that  a  further  distinction 
should  be  made,  between  rifled  and  smooth-bored  can- 
non. How  far  this  change  will  affect  the  distinction 
now  made  between  guns  and  howitzers,  remains  to  be 
determined  by  future  experience. 

In  treating  of  cannon,  it  is  proposed,  in  the  first 
place  to  discuss  those  parts  and  principles  common  to 
all ;  and,  in  the  second  place,  to  consider  the  peculiar 
characteristics  of  each  class  and  calibre. 

A.  .Cascable. 

B.  .First  reinforce. 

C.  .Sec'd  reinforce. 
D..  Chase. 

E.  .Swell  of  the  muz- 
zle. 

F.  .Trunnions. 

G.  .Rimbases. 
Fig.  26.                                                 H.  .Bore. 

82.  Womenciatnre.*  The  coscohle  is  that  part  of 
the  gun  in  rear  of  the  base  of  the  breech ;  it  is  com- 
posed generally  of  the  following  parts:  the  knob,  the 
neck,  the  fillet, 

*  This  nomenclature  refers  more  particularly  to  guns  of  the  old  pattern,  large 
numbers  of  which  will  probably  remain  in  service  for  some  time  to  come.  The 
most  recent  models  are  characterized  by  an  entire  absence  of  mouldings  and  orna- 
ments, and  the  elements,  in  most  cases,  are  curved  instead  of  right  lines.  The 
modifications  which  it  is  necessary  to  make  to  suit  the  present  nomenclature  to  the 
new  system,  will  readily  suggest  themselves  to  the  mind  cf  the  pupil. 


NOMENCLATURE.  115 

The  base  of  the  breech  is  a  frustum  of  a  cone,  or  a 
spherical  segment,  in  rear  of  the  breech. 

The  base-ring  is  a  projecting  band  of  metal  adjoining 
the  base  of  the  breech,  and  connected  with  the  body  of 
the  gun  by  a  concave  moulding.  It  serves  as  a  point 
of  support  for  the  breech  sight,  and  rests  upon  the 
head  of  the  elevating  screw.  The  ring  is  omitted  in 
guns  of  recent  model. 

The  breech  is  the  mass  of  solid  metal  behind  the 
bottom  of  the  bore,  extending  to  the  rear  of  the  base-ring. 

The  reinforce  is  the  thickest  part  of  the  body  of  the 
piece,  in  front  of  the  base-ring.  If  there  be  more  than 
one  reinforce,  that  which  is  next  to  the  base-ring  is 
called  the  first  reinforce  /  the  other,  the  second  rein- 
force. 

The  chase  is  the  conical  part  of  the  piece  in  front 
of  the  reinforce. 

The  astragal  and  fillets,  in  field  guns,  and  the  chase- 
ring  in  other  pieces,  are  the  mouldings  at  the  front 
end  of  the  chase. 

The  neck  is  the  smallest  part  of  the  piece,  in  front 
of  the  astragal  or  chase-ring. 

The  swell  of  the  muzzle  is  the  largest  part  of  the 
piece  in  front  of  the  neck.  It  is  terminated  by  the 
muzzle  mouldings,  which,  in  field  and  siege  guns,  con- 
sist of  the  lip  and  fillet.  In  sea-coast  guns,  and  heavy 
howitzers  and  columbiads,  there  is  no  fillet.  In  field 
and  siege  howitzers,  and  in  mortars,  a  muzzle  band 
takes  the  place  of  the  swell  of  the  muzzle. 

The  face  of  the  piece  is  the  terminating  plane  per- 
pendicular to  the  axis  of  the  bore. 

The  trunnions  are  cylinders,  the  axes  of  which  are 


116  CANNON. INTERIOR    FORM. 

in  a  plane  perpendicular  to  the  axis  of  the  bore,  both 
axes  being  in  the  same  plane. 

The  rimbases  are  short  cylinders,  uniting  the  trun- 
nions with  the  body  of  the  gun.  The  ends  of  the  rim- 
bases,  or  the  shoulders  of  the  trunnions,  are  planes  per- 
pendicular to  the  axis  of  the  trunnions. 

The  bore  of  the  piece  includes  all  that  part  bored 
out,  viz.:  the  cylinder,  the  chamber  (if  there  be  one), 
and  the  conical  or  spherical  surface  connecting  them. 

The  muzzle,  or  mouth  of  the  bore  is  chamfered,  in 
order  to  prevent  abrasion  and  facilitate  loading. 

The  lock-piece  is  a  block  of  metal  at  the  outer  open- 
ing of  the  vent  for  the  attachment  of  the  lock.  As 
friction-tubes  are  now  used  for  firing  cannon  in  the  land 
service,  this  part  is  omitted. 

The  natural  line  of  sight  is  a  line  drawn,  in  a  vertical 
plane  through  the  axis  of  the  piece,  from  the  highest 
point  of  the  base-ring  to  the  highest  point  of  the  swell  of 
the  muzzle,  or  to  the  top  of  the  sight  if  there  be  one. 

The  natural  angle  of  sight  is  the  angle  which  the 
natural  line  of  sight  makes  with  the  axis  of  the  piece. 

The  dispart  is  the  difference  of  the  semi-diameters 
of  the  base-ring  and  the  swell  of  the  muzzle,  or  muzzle- 
band.  It  is,  therefore,  the  tangent  of  the  natural  angle 
of  sight,  to  a  radius  equal  to  the  distance  from  the  rear 
of  the  base-ring  to  the  highest  point  of  the  swell  of  the 
muzzle,  the  sight,  or  the  front  of  the  muzzle-band,  as 
the  case  may  be. 

INTERIOR  FORM. 

83.  Division  of  parts.  The  interior  of  cannon  may 
be  divided  into  three  distinct  parts ;  1st,  the  vent,  or 


THE    VENT.  .  117 

channel  which  communicates  fire  to  the  charge  ;  2d,  the 
seat  of  ths  charge,  or  chamber,  if  its  diameter  be  differ- 
ent from  the  rest  of  the  bore ;  3d,  the  cylinder,  or  that 
portion  of  the  bore  passed  over  by  the  projectile. 

84.  The  vent.  The  size  of  the  vent  should  be  as  small 
as  possible,  in  order  to  diminish  the  escape  of  the  gas,  and 
the  erosion*  of  the  metal  which  results  from  it.  All  vents 
in  -the  United  States'  service  are  0.2  inch  in  diameter. 
In  bronze  pieces  which  fire  large  charges  of  powder, 
the  heat  of  the  imiamed  gases  would  be  sufficient  to 
melt  the  tin,  and  rapidly  enlarge  its  diameter.  For  this 
reason,  they  are  bushed  by  screwing  in  a  perforated 
piece  of  pure  wrought  copper,  called  the  vent-piece.   See 

fig.  27.  This  arrangement  al- 
lows the  vent  to  be  renewed 
when  too  much  enlarged  by 
continued  use,  or  when  closed 
with  a  spike. 

Position.     The  axis  of  the 
Fig.  27  vent   is   generally  situated  in 

a  plane  passing  through  the  axis  of  the  piece,  and 
at  right  angles  to  the  trunnions.  Formerly  it  made 
an  angle  of  80°  with  the  axis  of  the  piece,  measured 
from  the  rear,  but  in  nearly  all  pieces  of  new  model  it 
is  at  right  angles  to  this  line.  The  first,  or  oblique 
direction,  was  given  to  insure  the  pricking  of  the  car- 
tridge, in  case  it  was  not  rammed  completely  home ;  the 
perpendicular  position  is  given  to  prevent  the  body  of 
the  friction-tube  from  being  pulled  out  in  firing. 

*  It  is  stated  that  the  wear,  by  the  passage  of  the  gas  through  the  vent  of  the  large 
13-in.  wrought  gun  lately  tried  in  England,  was  so  great  as  to  require  rebushing 
after  every  nine  rounds.  Field  rifle-cannon  with  steel  vent- pieces  were  found  to 
require  rebushing  after  every  350  rounds  ;  copper  vent-pieces  having  been  found 
to  enlarge  very  slightly,  have  been  adopted  for  all  rifle  guns. 


118  CANNON. POSITION    OF    VENT. 

The  interior  orifice  of  the  vent  is  placed  at  a  distance 
from  the  bottom  of  the  chamber  eqnal  to  a  fourth  of 
its  diameter,  or  at  the  junction  of  the  sides  of  the  cham- 
ber with  the  curve  of  the  bottom.  Experiment  shows 
that  this  position  of  the  vent  is  more  favorable  to  the 
full  development  of  the  force  of  the  charge  than  any 
other  along  its  length. 

Many  authors  have  attributed  the  injuries  which  .are 
observed  to  take  place  about  the  lodgment  of  the  pro- 
jectile, to  the  position  of  the  vent  at  the  bottom  of  the 
bore,  supposing  that  the  evolution  of  the  elastic  gases 
begins  at  the  upper  portion  of  the  charge,  and  that  the 
projectile  is  consequently  pressed  down  upon  the  lower 
side  of  the  bore  before  it  is  set  in  motion.  To  remedy 
this,  it  was  proposed  to  place  the  orifice  at  the  centre  of 
the  bottom  of  the  bore ;  and  to  determine  the  merits  of 
this  proposition,  special  experiments  were  made  at  the 
artillery  schools  of  Douai,  Toulouse,  and  Strasbourg,  on 
new  guns  of  24  and  16  lbs.  calibre. 

The  first  gun  had  the  ordinary,  old-fashioned  vent ; 
see  fig.  27  (A) ;  in  the  second  the  orifice  of  the  vent 
was  placed  at  the  centre  of  the  bottom,  with  its  axis 
making  an  angle  of  30°  with  that  of  the  gun  (i?) ;  and 
the  third  had  its  orifice  at  the  centre  of  the  bottom, 
with  its  axis  coincident  with  that  of  the  gun  (  C). 

The  several  pieces  were  fired  under  the  same  circum- 
stances, and  the  injuries  noted  with  great  care.  It  was 
found  that  the  gun  with  the  ordinary  vent  had  only  ex- 
perienced slight  injuries,  while  the  others  became  un- 
serviceable in  a  few  rounds;  as  will  be  seen  by  an 
examination  of  the  following  table  : 


LOSS. 


119 


Position  of  the  vent. 

Depth  of  Lodgement. 

r 

Strasbourg 
24-pdr.  Gun. 

Toulouse 
24-pdr.   Guns. 

"'■  ^ 
Douai 
16-pdr.   Gun. 

Vent  in  the  axisJ 

Vent  inclined  30<»] 
Ordinary  vent 

37    points   after  J 
40  shots.          j 

34   points  after  j 
60  shots.          ( 

23  points  after  6  sh.  ( 
25     "         M    30  "    -j 

14£  "         "      6"    ( 
33     "         "    30  "    ] 

3     "         "    30  "    i 

8  points  aft.  6  sh. 
17     "         "  30  " 

24  "         "  60  " 
14     "         "  30  " 

25  "         «  90  " 

3  "         u  60  " 

4  "         "  90  " 

The  most  probable  explanation  of  these  results  is 
this :  In  guns  with  the  ordinary  vent,  the  gas  which  is 
developed  in  the  first  moments  of  combustion,  expands 
freely  into  the  space  between  the  top  of  the  cartridge 
and  bore ;  it  has  therefore  less  tension  when  it  passes 
over  the  ball,  which  will  have  been  moved  before  all 
the  charge  is  inflamed.  In  the  two  cases  in  which  the 
orifice  is  situated  at  the  centre  of  the  bottom,  the  gas 
formed  cannot  develop  itself  in  the  space  over  the 
charge,  but  it  expands  into  the  interstices  of  the  charge 
with  a  greater  tension  than  it  had  in  the  first  case,  and 
thereby  accelerates  the  inflammation  of  the  charge. 
From  this  it  follows,  that  the  ball  is  not  moved  from  its 
place  quite  so  soon  as  in  the  first  case,  but  it  begins  to 
move  at  an  epoch  more  nearly  approximating  that  of 
the  maximum  tension  of  the  gas  of  the  charge  ;  and  the 
pressure,  therefore,  of  the  gas  as  it  passes  over  the  ball, 
will  be  greater ;  which  will  account  for  the  greater 
depth  of  the  lodgment. 

85.  L-oss.  Experiment  also  shows  that  the  actual  loss 
of  force  by  the  escape  of  gas  through  the  vent,  as  com- 
pared to  that  of  the  entire  charge,  is  inconsiderable, 
and  may  be  neglected  in  practice. 


\ 
120         CANNON. SEAT  OF  THE  CHARGE. 


SEAT  OF  THE  CHARGE. 

86.  Seat  of  the  Charge.  The  form  of  that  part  of  the 
bore  of  a  fire-arm  which  contains  the  powder,  will  have 
an  effect  on  the  force  of  the  charge,  and  the  strength  of 
the  piece  to  resist  it. 

The  points  to  be  considered  as  most  likely  to  affect 
the  force  of  the  powder,  are,  the  form  of  the  surface, 
and  its  extent  compared  to  the  enclosed  volume.  In 
the  first  place,  to  obtain  the  full  force  of  a  charge,  its 
form  should  be  such  that  its  inflammation  will  be  nearly 
completed  before  the  gas  begins  to  escape  through  the 
windage,  and  the  projectile  is  sensibly  moved  from  its 
place — in  other  words,  the  length  of  the  space  occupied 
by  the  charge  should  be  nearly  equal  to  its  diameter ; 
in  the  second  place,  as  the  tension  depends  much  upon 
the  heat  evolved  by  the  combustion,  the  absorbing  sur- 
face should  be  a  minimum  compared  to  the  volume. 

87.  Heavy  charges.  The  charges  with  which  solid 
projectiles  are  generally  fired  being  greater  than  \  of 
their  weight,  the  cartridge  occupies  a  space,  the  length 
of  which  is  greater  than  the  diameter ;  in  cannon,  there- 
fore, which  fire  solid  projectiles,  the  form  of  the  seat  of 
the  charge  is  simply  the  bore  prolonged;  this  arrange- 
ment, when  compared  with  the  chamber,  makes  the 
absorbing  surface  of  the  metal  a  minimum,  and  reduces 
the  length  of  the  charge  so  that  its  inflammation  will 
be  as  complete  as  possible,  before  the  gas  escapes  and 
the  projectile  is  moved. 

To  give  additional  strength  to  the  breech,  and  to 
prevent  the  angle  formed  by  the  plane  of  the  bottom 


LIGHT    CHARGES.  121 

and  sides  of  the  bore  from  becoming  a  receptacle  for 
dirt,  and  burning  fragments  of  the  cartridge-bag,  it  is 
rounded  with  the  arc  of  a  circle  whose  radius  is  one- 
fourth  the  diameter  of  the  bore  at  this  point.  See  fig. 
27.  Instead  of  being  a  plane  bottom,  it  is  sometimes 
made  hemispherical,  tangent  to  the  surface  of  the  bore. 
In  all  cannon  of  the  most  recent  model,  the  bottom  of 
the  bore  is  a  semi-ellipsoid.  This  is  thought  to  fulfil 
the  condition  of  strength  more  fully  than  the  hemi- 
sphere. 

88.  L-igiit  charges.  When  a  light  piece  is  used  to 
throw  a  projectile  of  large  diameter  and  great  weight, 
the  effect  of  the  recoil  can  only  be  diminished  by  em- 
ploying a  small  charge  of  powder. 

If  such  a  charge  were  made  into  a  cartridge  of  a 
form  to  fit  the  bore,  its  length  would  be  less  than  its 
diameter,  and  being  ignited  at  the  top,  a  considerable 
portion  of  the  gas  generated  in  the  first  instants  of  in- 
flammation, would  pass  through  the  windage,  and  a 
part  of  the  force  of  the  charge  would  be  lost. 

To  obviate  this  defect,  to  give  the  cartridge  a  more 
manageable  form  in  loading,  and  to  make  the  surface 
a  minimum,  as  regards  the  volume,  the  diameter  of  this 
part  of  the  bore  is  reduced  so  as  to  form  a  chamber. 

The  shape  of  the  chambers  of  fire-arms  is  either 
cylindrical,  conical,  or  spherical. 

The  effect  of  these  different  forms  of  chambers  on 
the  velocity  of  the  projectile  will  be  modified  by  the 
size  of  the  charge  and  the  length  of  the  bore.  Up  to 
a  charge  of  powder  equal  to  \  of  the  weight  of  the 
projectile,  and  a  length  of  bore  equal  to  9  or  10  calibres, 
experience  shows  that  the  presence  of  a  chamber  is  ad- 


122 


CANNON. SEAT  OF  THE  CHARGE. 


vantageous ;  but  beyond  these,  it  possesses  no  advan- 
tages to  compensate  for  its  inconvenience. 

Cylindrical  chamber.  For  very  small  charges  of  pow- 
der, and  short  lengths  of  bore, 
the  cylindrical  chamber  gives  bet- 
ter results  than  the  conical  cham- 
ber. This  may  be  explained  by 
the  fact,  that  in  this  chamber  the 
charge  acts  a  longer  time  on  the 
projectile,  inasmuch  as  it  acts  on 
a  smaller  portion  of  its  surface,  and  the  grains  of  pow- 
der are  therefore  more  completely  consumed  when  the 
projectile  leaves  the  piece.  But  for  larger  charges  the 
conical  chamber  is  found  to  answer  best ;  which  may 
be  seen  from  the  following  table  taken  from  actual 
firing : 


Fig.  28. 


MORTARS. 

CHARGE. 

CYLINDRICAL   CHAMBER. 

CONICAL    CHAMBER. 

10-inch. 

1.10  lbs. 

456  meters. 

390  meters. 

u 

1.65    " 

790       " 

695 

t» 

2.20    " 

1060       " 

969        " 

a 

2.75    " 

1290    .  " 

1297 

M 

7.00    " 

2530        " 

u 

7.90    " 

2530       " 

2750       " 

8-inch. 

0.50    " 

325       " 

210 

u 

0.60    " 

775       " 

540 

u 

1.30    " 

1250 

1308        " 

Note. — Supposed  to  have  been  fired  at  45  °  elevation. 


Conical  chambers.  For  the  same  capacity,  the  coni- 
cal chamber  gives  a  shorter  cartridge,  and  is  therefore 
better  suited  to  the  rapid  inflammation  of  a  large 
charge  of  powder   than   the  cylindrical  chamber.     It 


EFFECT    ON    STRENGTH. 


123 


Fig.  29. 


also  presents  less  surface  of, 
metal  for  the  absorption  of 
heat.  The  particular  kind  of 
chamber  represented  in  the  di- 
agram is  called  a  Gomer  cham- 
ber, after  its  inventor.  Its  prin- 
cipal advantages  are,  that  of  distributing  the  force  of 
the  charge  over  a  large  portion  of  the  surface  of  the 
projectile,  thereby  rendering  it  less  liable  to  break,  if  it 
be  hollow;  and  that  of  destroying  the  windage  when 
the  projectile  is  driven  down  to  its  proper  place. 

Spherical  chamber.  This  chamber  was  formerly  used 
in  mortars,  but,  owing  to  the  inconveniences  which 
attend  its  construction  and  use,  and  its  liability  to 
deterioration,  it  is  now  entirely 
abandoned.  Experiment  shows 
that  when  a  chamber  of  this 
kind  is  entirely  filled  with  pow- 
der, it  gives  a  greater  initial  ve- 
locity to  the  projectile  than  any 
other ;  and  this,  probably,  for  the  reasons  that  its  form 
is  better  suited  to  the  rapid  inflammation  of  the  charge  ; 
that  it  has  the  least  surface  compared  to  its  capacity ; 
that  sensible  motion  does  not  take  place  so  soon;  and 
that  the  escape  of  gas  by  windage  is  comparatively 
small. 

Other  forms  of  chambers,  such  as  the  parabolical, 
hyperbolical,  <fec,  have  been  proposed,  but  experiment 
has  failed  to  show  that  they  possess  any  advantages 
over  other  and  more  simple  forms. 

89.  Effect  on  strength.  No  very  careful  experiments 
have  been  made  to  determine,  in  a  general  way,  the 


Fig.  30. 


124  CANNON. WINDAGE. 

effect  of  the  chamber  on  the  strength  of  cannon ;  but 
late  experience  indicates  that  cylindrical  chambers  in 
heavy  iron  guns,  have  an  injurious  effect  on  their  en- 
durance, and  they  have  consequently  been  abandoned 
in  these  pieces.  / 

WINDAGE. 

90.  Definition.  Windage  is  the  space  left  between 
the  bore  of  a  piece  and  its  projectile,  and  is  measured 
by  the  difference  of  their  diameters.  The  objects  of 
windage  are  to  facilitate  loading,  and  to  diminish  the 
danger  of  bursting  the  piece ;  it  is  rendered  necessary 
by  the  mechanical  impossibility  of  making  every  pro- 
jectile of  the  proper  size  and  shape,  by  the  unyielding 
nature  of  the  material  of  which  large  projectiles  are 
made,  by  the  foulness  which  collects  in  the  bore  after 
each  discharge,  and  by  the  use  of  hot  and  strapped 
shot. 

The  true  windage,  which  is  the  difference  between 
the  true  diameters  of  the  bore  and  projectile,  increases 
slightly  with  the  size  of  the  bore,  and  is  greater  for 
solid  shot,  which  are  sometimes  fired  hot,  than  for 
hollow  projectiles,  which  are  never  heated. 

91.  L.©§s  of  force.  The  ordinary  windage  of  smooth- 
bored  cannon,  used  in  the  United  States'  service,  is 
about  TV  of  the  diameter  of  the  bore,  and  the  loss  of 
force  arising  from  the  escape  of  gas  through  this  wind- 
age amounts  to  a  very  considerable  portion  of  the 
entire  charge. 

The  amount  of  loss  in  any  case  depends  on 


WINDAGE. 


125 


1.  The  degree  of  windage  ; 

2.  The  calibre  of  the  gun ; 

3.  The  length  of  the  bore  ; 

4.  The  kind  of  powder ; 

5.  The  charge  of  powder ; 

6.  The  weight,  or  density  of  the  ball. 

It  is  probable  that  the  influence  which  some  of  these 
causes  exert  on  the  force  of  the  charge  is  very  slight ; 
and  that  to  determine  the  exact  influence  of  each  of 
the  others  would  be  a  very  difficult  if  not  an  imprac- 
ticable problem. 

The  most  important  question  is,  to  determine  what 
allowance  must  be  made  for  a  given  difference  of  ordi- 
nary windage. 

The  pressure,  or  force,  exerted  by  a  charge  of  powder 
on  different  balls  at  the  same  point  of  the  bore  of  a 
piece,  will  be  proportioned  to  the  surfaces,  or  squares 
of  their  diameters.  If  the  weight  of  the  balls  be  the 
same,  the  pressure  will  be  proportional  to  the  square 
of  the  velocity  communicated  to  the  balls  in  a  given 
time.     We,  therefore,  have  the  proportion — 


D* 

d2  : 

:    Vs  :  v2 

and  D2 

d'2: 

:    Vs  :  v2 

or  D 

d    : 

:   V    :  v 

and  D 

d'   : 

:    V    :  »' 

hese  last  two  proportions  we  have 

D  :  D-d  : :    V  :   V-v 

D  :  D-d'::    V:    V-v' 

or  D—d : 

D-d 

'::    V--v  :   V—v' 

In  which,  D,  d,  and  d'  represent  the  diameters  of  three 
balls,  and  F",  vy  vr  their  initial  velocities,  respectively. 
If  D  equal  the  diameter  of  the  bore,  D— d  is  the  wind- 


126  CANNON. WINDAGE. 

age  of  the  ball  whose  diameter  is  d,  and  D—d'  is  the 
windage  of  the  ball  whose  diameter  is  d'.  If  we  mul- 
tiply the  extremes  and  means  of  the  last  proportion,  and 
divide  the  resulting  equation  by  V  (D— d),  we  shall 
have  the  expression 

v-v'   /n    ,N    v-v 

-T-={D-d)irw-Ty 

V—v 

By  making  m=  „,^      ,1  the  equation  becomes 

V-V'=Vxm(D-d'). 

This  equation  expresses  the  relation  between  a  certain 
windage,  D— aT  and  the  loss  of  velocity  due  to  that 
windage,  or  V—v'. 

In  a  series  of  experiments  made  by  Major  Mordecai, 
with  the  ballistic  and  gun  pendulums,  it  was  found  that 
m  was  constant  for  all  values  of  D—d'  that  would  be 
likely  to  arise  in  service.  From  this  it  follows  that  V 
—v'  is  proportional  to  D—d ';  or,  in  other  words,  that 
the  loss  of  velocity  by  windage  is  proportional  to  the 
windage. 

When  the  charge  of  powder  was  varied,  it  was  found 
that  the  absolute  loss  of  velocity  by  a  given  increase  of 
windage,  was  very  nearly  the  same  for  all  the  charges 
used.  It  follows  from  this  tlmt  the  proportional  loss  is 
less  for  the  higher  charges. 

Both  the  absolute  and  relative  loss  of  velocity  by  a 
given  difference  of  windage  (say  one-tenth  of  an  inch) 
increase  as  the  calibre  of  the  piece  decreases. 

From  the  foregoing,  it  may  be  stated,  that  the  loss  of 
velocity  by  a  given  windage,  is  directly  as  the  windage, 
and  inversely  as  the  diameter  of  the  bore,  very  nearly. 


LENGTH   OF    BORE.  127 

The  loss  of  velocity  of  a  24-pdr.  ball  by  a  windage 
of  ^-,  and  a  charge  of  6  lbs.  of  powder,  is  9  per  cent. 

LENGTH  OF  BORE. 

92.  Ancient  theory.  The  slow  rate  of  burning  of 
mealed  powder,  which  was  originally  used  in  cannon, 
led  to  the  belief  that  the  longest  pieces  gave  the  great- 
est ranges.  In  spite  of  much  experience  to  the  con- 
trary, this  belief  was  entertained,  even  after  gunpowder 
received  its  granular  form ;  and  several  pieces  were 
made  of  enormous  length,  with  the  expectation  of  real- 
izing corresponding  ranges.  s 

A  culverin  was  cast  during  the  reign  of  Charles  V. 
which  was  58  calibres  long,  and  fired  a  ball  weighing 
36  lbs.;  but  on  trial,  this  piece  was  found  to  have 
actually  less  range  than  an  ordinary  12-pdr.  gun. 

The  experiment  of  reducing  its  length,  by  successively 
cutting  it  off  to  50,  44,  and  43  calibres,  was  tried,  and 
it  was  found  that  the  range  increased  at  each  reduction 
until  it  gained  2,000  paces. 

93.  What  governs  the  length.  That  the  length  of  the 
bore  has  an  important  effect  on  the  velocity  of  the 
projectile,  will  be  readily  seen  by  a  consideration  of 
the  forces  which  accelerate  and  retard  its  movement  in 
the  piece. 

The  accelerating  force  is  due  to  the  expansive  effort 
of  the  inflamed  powder,  which  reaches  its  maximum 
when  the  grains  of  the  charge  are  completely  converted 
into  vapor  and  gas.  This  event  depends  on  the  size 
of  the  charge,  and  the  size  and  velocity  of  combustion 
of  the  grains.     With  the  same  accelerating  force,  the 


128  CANNON. LENGTH  OF  BORE. 

point  at  which  a  projectile  reaches  its  maximum  velocity- 
depends  on  its  density,  or  the  time  necessary  to  over- 
come its  inertia. 

The  retarding  forces  are — 1st.  The  friction  of  the 
projectile  against  the  sides  of  the  bore :  this  is  the 
same  for  all  velocities,  but  different  for  different  metals; 
2d.  The  shocks  of  the  projectile  striking  against  the 
sides  of  the  bore :  these  will  vary  with  the  angle  of  in- 
cidence, which  depends  on  the  windage,  and  the  extent 
of  the  injury  due  to  the  lodgment  and  balloting  of  the 
projectile ;  3d.  The  resistance  offered  by  the  column  of 
air  in  front  of  the  projectile :  this  force  will  increase  in 
a  certain  ratio  to  the  velocity  of  the  projectile  and 
length  of  the  bore. 

As  the  accelerating  force  of  the  charge  increases  up 
to  a  certain  point,  after  which  it  rapidly  diminishes,  as 
the  space  in  rear  of  the  projectile  increases,  and  as  the 
retarding  forces  are  constantly  opposed  to  its  motion,  it 
follows,  that  there  is  a  point  where  these  forces  are 
equal  and  the  projectile  moves  with  its  greatest  velocity ; 
it  also  follows  that  after  the  projectile  passes  this  point, 
its  velocity  decreases  until  it  is  finally  brought  to  a  state 
of  rest,  which  would  be  the  case  in  a  gun  of  great  length. 

94.  Experiments  to  determine  it.  Elaborate  experi- 
ments have  been  made  in  this  country  and  abroad,  to 
determine  accurately  the  influence  which  the  length  of 
the  piece  exercises  on  the  velocity  of  its  projectile. 

The  curves  in  the  accompanying  figure  show  to  the 
eye  the  relation  existing  between  the  different  lengths 
of  the  bore  of  a  12-pdr.  gun  and  the  corresponding 
velocities,  for  charges  of  2.2,  3.3,  and  4.4  lbs. 

The  ordinates  represent  the  lengths  of  the  bore  in 


CONCLUSIONS. 


129 


calibres,  and  the  abscissas  represent  the  velocities,  as 
determined  by  the  electro-ballistic  pendulum. 


Length  in  calibres 
ii 

M 

(( 
(( 
II 

20.8 
18.3 
15.8 
13.3 
10.8 
8.3 
5.8 

V 

e 

1 

o 

cities 

1 

22  lbs.           3-  Jibs. 

A-UIbs. 

_J | 

/                                      / 

/                    /               /                 1 

/        /    y        1 

s        /  / 

s^^^ 

1 

Pig.  31. 


An  inspection  of  the  figure  shows  that  the  velocity 
increases  with  the  length  of  the  bore  in  a  variable  ratio, 
the  increase  of  velocity  for  the  short  lengths  being  much 
greater  than  for  the  long  lengths. 

The  experiments  made  by  Major  Mordecai,  some  years 
before  these,  on  a  gun  of  the  same  calibre,  show  that 
the  velocity  increases  with  the  length  of  the  bore  up  to 
25  calibres ;  but  that  the  entire  gain  beyond  16  calibres, 
or  an  addition  of  more  than  one  half  to  the  length  of  the 
gun,  gives  an  increase  of  only  one -eighteenth  to  the  effect 
of  a  charge  of  4  lbs. 

95.  Conclusions.  It  follows  from  the  foregoing,  that 
the  length  of  bore  which  corresponds  to  a  maximum 
velocity,  depends  upon  the  projectile,  charge  of  powder, 
and  material  of  which  the  piece  is  made ;  and  taking 
the  calibre  as  the  unit  of  measure,  it  is  found  that  this 
length  is  greater  for  small  arms,  which  fire  leaden  pro- 
jectiles, than  for  guns  which  fire  solid  iron  shot,  and 
greater  for  guns  than  for  howitzers  and  mortars,  which 

fire  hollow  projectiles. 
9 


130  CANNON. CHAEGE. 

For  the  same  charge  of  powder,  it  may  be  said  that 
the  initial  velocity  of  a  projectile  varies,  nearly,  with  the 
fourth  root  of  the  length  of  the  bore,  provided  the  varia- 
tion in  length  be  small. 


CHARGE. 

96.  Maximum  charge.  By  increasing  the  charge  of 
powder  of  a  fire-arm,  the  greater  and  (in  consequence 
of  the  wedging  of  the  unburned  grains  among  each 
other)  the  more  difficult  will  be  the  mass  to  be  set  in 
motion ;  the  space  between  the  front  of  the  charge  and 
the  muzzle  will  be  diminished ;  and  a  larger  number  of 
grains  will  be  thrown  out  unconsumed.  It  is  evident, 
therefore,  that  the  effect  of  a  charge  of  powder  on  a 
projectile  should  not  increase  with  the  size  of  the 
charge;  and  experiment  shows  that  beyond  a  certain 
point,  an  increase  of  charge  is  actually  accompanied 
with  a  loss  of  velocity.  The  charge  corresponding  to 
this  point  is  called  the  maximum  charge. 

The  following  are  the  results  of  experiments  made 
in  France  on  a  36-pounder  gun,  of  16  calibres  in  length : 

Charge,  lbs.,     .     .  36,       42,     49,     56,     70,    77. 

Initial  velocity,  feet,     1,320,  1,170,  950,  493,  454,  191. 

It  will  therefore  be  seen  that  an  excess  of  charge  is 
almost  as  injurious  to  the  velocity  of  a  projectile,  as  an 
excess  of  length  of  bore. 

97.  Effect§  on  recoil.  Trials  made  at  Turin  show  that 
the  recoil,  and  consequently  the  strain  on  the  gun  and 
carriage,  increase  in  a  more  rapid  ratio  than  the  charges, 


MATERIALS.  131 

viz.:  14  lbs.  of  powder  gave  a  recoil  of  70  inches;  15 
lbs.,  72  inches;  16  lbs.,  74  inches;  18  lbs.,  100  inches. 

98.  Effect  of  length  of  bore  on  maximum  charge.   All 

experience  proves  that  the  longer  a  piece  is,  in  terms  of 
its  calibre,  the  greater  will  be  the  maximum  charge  in 
proportion  to  the  weight  of  the  projectile.  For  heavy 
cannon,  19  to  20  calibres  long,  the  maximum  charge  may 
be  stated  to  be  £  the  weight  of  the  projectile ;  and  for 
light  cannon  of  the  same  length,  \  to  -§-  of  this  weight ; 
the  increase  of  range  for  charges  above  \  the  weight 
of  the  projectile,  being  very  small. 

99.  Most  §uitabie  charge.  A  charge  of  \  the  weight 
of  the  projectile,  and  a  bore  of  18  calibres,  is  the  most 
favorable  combination  that  can  be  made  in  smooth- 
bored  cannon,  to  obtain  the  greatest  range  with  the 
least  strain  to  the  carriage. 

In  the  early  days  of  artillery,  when  dust  instead  of 
grained  powder  was  used  in  cannon,  the  weight  of 
the  charge  was  equal  to  that  of  the  projectile ;  after 
the  introduction  of  grained  powder,  it  was  reduced 
to  |,  and  in  1740  to  £,  this  weight. 


MATERIALS. 

100.  Requirements.  Before  discussing  the  exterior 
form  of  cannon,  it  is  necessary  to  study  the  nature 
of  the  materials  of  which  they  are  composed.  The 
selection  of  a  suitable  material  is  a  very  important 
consideration  in  the  construction  of  cannon,  in  conse- 
quence of  the  great  difficulty  of  obtaining  any  one 
that  possesses  all  the  qualities  required  of  it. 


132  CANNON. MATEEIALS. 

The  qualities  necessary  in  cannon-metals  are,  strength 
to  resist  the  explosion  of  the  charge,  weight  to  overcome 
severe  recoil,  and  hardness  to  endure  the  bounding  of 
the  projectile  along  the  bore. 

101.  strength.  The  term  strength,  as  applied  to  a 
cannon-metal,  should  not  be  confined  to  tensile  strength 
alone,  which  expresses  the  ability  of  a  substance  to 
resist  rupture  from  extension  produced  by  a  simple 
pressure,  as  a  weight,  but  should  embrace  a  knowledge 
of  its  elasticity,  ductility,  and  crystalline  structure,  which 
affect  its  power  to  resist  the  enormous  and  oft-repeated 
force  of  gunpowder — a  force  which  resembles  a  blow, 
in  the  rapidity  of  its  application. 

Elasticity.  It  has  been  shown  by  experiment,  that 
the  feeblest  strains  produce  permanent  elongation  or 
compression  in  iron  ;  and  the  same  is  probably  true  of 
all  other  materials.  Perfect  elasticity  cannot,  there- 
fore, be  found  in  solids,  although  different  substances 
possess  it  in  different  degrees.  It  follows  that  each 
discharge,  however  small,  must  impair  the  strength  of 
a  cannon,  and  an  ordinary  discharge,  repeated  a  suf- 
ficient number  of  times,  will  burst  it. 

In  the  selection  of  a  durable  cannon-metal,  it  is 
necessary  to  know,  not  only  the  ultimate  rupturing 
force,  but  also  the  relation  between  lesser  forces,  and 
the  extension  and  compression  produced  by  them,  and 
the  permanent  extension,  or  compression,  which  remains 
after  these  forces  are  withdrawn,  or  what  is  technically 
known  as  the  "  permanent  set."  This  knowledge  will 
be  useful  in  regulating  the  charge  of  a  cannon  to  suit 
the  required  endurance. 

Ductility.    Ductility  is  the  property  which  a  metal 


MATERIALS.  133 

possesses  of  changing  its  form,  without  rupture,  after  it 
has  passed  its  elastic  limit,  under  the  operation  of  ex- 
traneous forces,  and,  for  present  purposes,  may  be  con- 
sidered as  opposed  to  brittleness.  « 

Of  two  metals  that  possess  the  same  tensile  strength 
and  elasticity,  it  is  evident  that  it  will  require  more 
"  work"  to  rupture  the  one  which  possesses  the  greatest 
amount  of  ductility. 

Crystalline  structure.  The  size  and  arrangement  of 
the  crystals  of  a  metal,  have  an  important  influence  on 
its  strength  to  resist  a  particular  force.  This  arises  from 
the  fact  that  the  adhesion  of  the  crystals,  by  the  contact 
of  their  faces,  is  less  than  the  cohesion  of  the  particles 
of  the  crystals  themselves,  and  that,  consequently,  rup- 
ture takes  place  along  the  larger,  or  principal  crystalline 
faces. 

A  metal  will  be  strongest,  therefore,  when  its  crystals 
are  small,  and  the  principal  faces  are  parallel  to  the 
straining  force,  if  it  be  one  of  extension,  and  perpen- 
dicular to  it,  if  it  be  one  of  compression. 

The  size  of  the  crystals  of  a  particular  metal  depends 
on  the  rate  of  cooling  of  the  heated  mass :  the  most 
rapid  cooling  gives  the  smallest  crystals.  Practically, 
there  is  a  limit  to  the  rate  of  cooling  of  certain  metals ; 
cast  iron,  for  instance,  is  supposed  to  change  its  nature 
by  losing  a  portion  of  its  uncombined  carbon,  when 
suddenly  cooled,  as  in  iron  moulds. 

The  position  of  the  principal  crystalline  faces  of  a 
cooling  solid,  is  found  to  be  parallel  to  the  direction  in 
which  the  heat  leaves  it,  or  in  a  direction  perpendicular 
to  the  cooling  surface. 

The  result  of  this  arrangement  of  crystals  is  to  create 


134  CANNON. MATERIALS. 

planes  of  weakness  where  the  different  systems  of  crys- 
tals intersect.  Figure  32  represents  sections  of  the 
cylinders  of  two  hydraulic  presses,  used  in  the  construc- 
tion of  the  Britannia  Bridge.  The  bottom  of  No.  2, 
which  was  flat,  gave  way  along  the  lines  of  weakness 

A  B  and  C  D,  while 
No  1,  which  was  hemi- 
spherical, and  present- 
ed no  lines  of  weak- 
ness, resisted  all  the 
Fi£- 32-  pressure  applied  to  it. 

The  effect  of  this  law  on  the  strength  of  cannon  seems 
to  have  been  first  noticed  by  Mr.  Mallet ;  and  its  truth 
has  been  confirmed  in  several  instances  by  Captain  Rod- 
man, of  the  ordnance  department,  who  finds  that  radial 
specimens  are  more  tenacious  than  those  cut  tangentially 
from  the  same  gun. 

102.  Effect  of  cooling.  All  solid  bodies  contract  their 
size  in  the  operation  of  cooling.  It  follows,  therefore, 
that  if  the  different  parts  of  a  body  cool  unequally,  they 
will  contract  unequally,  and  the  body  will  change  its 
form,  provided  it  be  not  restrained  by  the  presence  of  a 
superior  force ;  if  it  be  so  restrained,  the  contractile  force 
will  diminish  the  adhesion  of  the  parts  by  an  amount 
which  depends  on  the  rate  of  cooling  of  the  different 
parts,  and  the  contractibility  of  the  metal. 

This  is  an  important  consideration  in  estimating  the 
strength  and  endurance  of  cannon,  particularly  those 
made  of  cast  iron,  as  will  be  seen  by  examining  the  form 
of  the  casting  and  the  method  of  cooling  it. 

The  general  form  of  the  casting  is  that  of  a  solid  frus- 
tum of  a  cone ;  it  is,  therefore,  cooled  from  the  exterior, 


EFFECT    OF   COOLING.  135 

which  causes  the  thin  outer  layer  to  contract  first,  and 
force  the  hotter  and  more  yielding  metal  within,  toward 
the  opening  of  the  mould.  Following  this,  the  adjacent 
layer  cools,  and  tends  to  contract ;  but  the  exterior  layer, 
to  which  it  coheres,  has  become  partially  rigid,  and  does 
not  fully  yield  to  the  contraction  of  the  inner  layer. 
The  result  is,  the  cohesion  of  the  particles  of  the  inner 
layer  is  diminished  by  a  force  of  extension,  and  that  of 
the  outer  layer  increased  by  a  force  of  compression. 

As  the  cooling  continues,  this  operation  is  repeated 
until  the  whole  mass  is  brought  to  a  uniform  tempera- 
ture ;  and  the  straining  force  is  increased  to  an  extent 
which  depends  on  the  size  and  form  of  the  mass,  the 
rapidity  with  which  it  is  cooled,  and  the  contractibility 
of  the  particular  metal  used. 

All  cannon,  therefore,  that  are  cooled  from  the  exte- 
rior are  affected  by  two  straining  forces — the  outer  por- 
tion of  the  metal  being  compressed,  and  the  interior 
extended,  in  proportion  to  their  distances  from  the  neu- 
tral axis,  or  line  composed  of  particles  which  are  neither 
extended  nor  compressed  by  the  cooling  process. 

The  effect  of  this  unequal  contraction  may  be  so  great 
as  to  crack  the  interior  metal  of  cast-iron  cannon,  even 
before  it  has  been  subjected  to  the  force  of  gunpowder; 
and  chilled  rollers,  which  are  cooled  very  rapidly  by 
casting  them  in  iron  moulds,  have  been  known  to  split 
open  longitudinally,  from  no  other  cause  than  the  enor- 
mous strains  to  which  they  are  thus  subjected. 

The  strain  produced  by  the  action  of  a  central  force, 
as  gunpowder  acting  in  a  cannon,  is  not  distributed 
equally  over  the  thickness  of  metal.  Barlow  shows 
that  it  diminishes  as  the  square  of  the  distance  from  the 


136  CANNON. MATERIALS. 

centre  increases*  It  follows  from  this,  that  the  sides  of 
a  cannon  are  not  rent  asnnder  as  by  a  simple  tensile 
force,  but  they  are  torn  apart  like  a  piece  of  cloth,  com- 
mencing at  the  surface  of  the  bore.  This  is  confirmed 
by  experience;  for  the  inner  portion  of  the  fractured 
surface  of  a  ruptured  gun,  is  found  to  be  stained  with 
the  smoke  of  the  powder,  while  the  outer  portion  is  un- 
touched by  it. 

It  will  thus  be  seen  that  the  effect  of  ordinary  cooling 
is,  to  diminish  the  strength  and  hardness  of  the  metal  of 
cannon  at,  or  near,  a  point  where  the  greatest  strength 
and  hardness  are  required,  i.  e.y  at  the  surface  of  the 
bore. 

Circumstances  affecting  it.  The  strains  produced  by 
unequal  cooling  increase  with  the  diameter  of  the  cast- 
ing, and  the  irregularity  of  its  form.  This  explains  the 
great  difficulty  which  is  found  in  making  large  cast-iron 
cannon  proportionally  as  strong  as  small  ones ;  and  also, 
how  it  is  that  projections,  like  bands,  mouldings,  &c, 
injure  the  strength  of  cannon.  It  also  explains  why 
cannon  made  of  "  high?'1  cast  iron,  or  cast  iron  made  more 
tenacious  by  partial  decarbonization,  are  not  so  strong 
as  cannon  made  of  weaker  iron ;  for  it  is  well  known 
that  such  iron  contracts  more  than  the  latter  in  cooling, 
and  therefore  produces  a  greater  strain  of  extension  on 
the  surface  of  the  bore. 

Rodmarfs  plan.  The  foregoing  considerations  led 
Captain  Kodman  to  propose  a  plan  for  cooling  cannon 
from  the  interior,  hoping  thereby  to  reverse  the  strains 


*  From  this  law  it  can  be  shown  that  a  piece  with  a  thickness  of  metal  equal  to 
one  calibre,  experiences  nine  times  greater  strain  on  the  surface  of  the  bore  than  on 
the  exterior. 


WEIGHT,    HARDNESS,    ETC.  137 

produced  by  external  cooling,  and  make  them  con- 
tribute to  the  endurance  rather  than  to  the  injury  of 
the  piece. 

The  method  employed  is,  to  carry  off  the  internal 
heat  by  passing  a  stream  of  water  through  a  hollow 
core,  inserted  in  the  centre  of  the  mould-cavity  before 
casting,  and  to  surround  the  flask  with  a  mass  of 
burning  coals  to  prevent  too  rapid  radiation  from  the 
exterior. 

Extensive  trials  have  been  made  to  test  the  merits  of 
this  plan ;  and  the  results  show  that  cast-iron  cannon 
made  by  it  are  not  only  stronger  but  are  less  liable  to 
enlargement  of  the  bore  from  continued  firing. 

Indications  were  shown,  however,  in  these  and  in 
other  trials,  that  the  strains  produced  by  unequal  cool- 
ing are  modified  by  time,  which  probably  allows  the 
particles  to  accommodate  themselves,  to  a  certain  extent, 
to  their  constrained  position,  as  in  the  case  of  a  bent 
spring  or  hoop. 

103.  Weight.  When  a  material  possesses  great  strength, 
but  cannot  be  easily  wrought  into  a  heavy  mass,  it  is 
customary  to  diminish  the  recoil  by  applying  an  ex- 
traneous weight  to  the  piece,  or  by  some  contrivance 
for  increasing  the  weight  or  friction  of  the  carriage. 
It  is  evident  that  these  methods  want  that  unity  and 
solidity  which  are  necessary  to  great  endurance  in  can- 
non. 

104.  Hardness.  Without  a  certain  degree  of  hardness, 
the  shape  of  the  bore  will  be  rapidly  altered  by  the  ac- 
tion of  the  projectile,  and  the  accuracy  and  safety  of  the 
piece  will  be  destroyed. 

In  rifle  cannon,  hardness  is  particularly  necessary,  to 


138  CANNON. MATERIALS. 

enable  the  spiral  grooves  to  resist  this  action ;  at  least, 
the  surface  of  the  bore  should  be  relatively  harder  than 
the  projectile. 

105.  Corrosion,  &c  Cannon  metals  should  be  able  to 
resist  the  corroding  action  of  the  atmosphere,  and  the 
heat  and  the  products  of  combustion  of  the  powder; 
should  be  susceptible  of  being  easily  bored  and  turned ; 
and  should  not  be  too  costly,  on  account  of  the  great 
number  and  weight  of  cannon  required  for  the  military 
service. 

106.  Kind  of  Metai§.  The  principal  materials  hereto- 
fore used,  in  the  fabrication  of  cannon,  are  bronze,  steel, 
wrought  iron,  and  cast  iron,  each  of  which  possesses  its 
peculiar  advantages  and  disadvantages. 

107.  Bronze.  Bronze  for  cannon  (commonly  called 
brass),  consists  of  90  parts  of  copper  and  10  of  tin,  al- 
lowing a  variation  of  one  part  of  tin,  more  or  less.  By 
increasing  the  proportion  of  tin,  bronze  becomes  harder, 
but  more  brittle  and  fusible ;  by  diminishing  it,  it  be- 
comes too  soft  for  cannon,  and  at  the  same  time  loses  a 
part  of  its  elasticity.  Bronze  is  more  fusible  than  cop- 
per, much  less  so  than  tin,  more  sonorous,  harder,  and 
less  susceptible  of  oxidation,  and  much  less  ductile  than 
either  of  its  constituents.  Its  fracture  is  of  a  yellowish 
color,  with  little  lustre,  a  coarse  grain,  irregular,  and  often 
exhibiting  spots  of  tin,  which  are  of  a  whitish  color. 
These  spots  indicate  defects  of  metal,  which  are  sup- 
posed to  arise  from  a  disposition  of  the  ingredients  to 
separate,  in  the  melted  state,  into  two  distinct  alloys,  or 
chemical  compounds,  possessing  different  degrees  of  fus- 
ibility. The  amount  of  tin  which  the  lighter-colored 
alloy  contains,  never  exceeds  25  per  cent. 


KIND    OF    METALS. STEEL. 


139 


Properties.  The  density  and  tenacity  of  bronze,  when 
cast  into  the  form  of  cannon,  are  found  to  depend  npon 
the  pressure  and  mode  of  cooling.  This  is  exhibited 
by  the  mean  of  observations  made  on  five  guns  cast  at 
the  Chickopee  Foundry,  viz. : 


Density. 

Tenacity  per  square  inch. 

Breech-square. 

Gun-head. 

Finished  Gun. 

Breech-square. 

Gun-head. 

1           8.765 

8.444                     8.740 

46.509  lbs. 

27.415 

The  guns  were  cast  in  a  vertical  position,  with  the 
breech-square  at  the  bottom. 

In  consequence  of  the  difference  of  fusibility  of  tin 
and  copper,  the  perfection  of  the  alloy  depends  much 
on  the  nature  of  the  furnace,  and  the  treatment  of  the 
melted  metal.  By  these  means  alone,  the  tenacity  of 
bronze  has  been  lately  carried,  at  the  Washington  Navy- 
Yard  Foundry,  as  high  as  60,000  lbs. 

Bronze  is  but  slightly  corroded  by  the  action  of  the 
gases  evolved  from  gunpowder,  or  by  atmospheric 
causes;  but  its  tin  is  liable  to  be  melted  away  at  the 
sharp  corners  by  the  great  heat  generated  by  rapid 
iiring.  It  is  soft,  and  therefore  liable  to  serious  injury 
by  the  bounding  of  the  projectile  in  the  bore:  this 
injury  is  augmented,  as  the  force  of  the  rebound  is 
increased  by  the  elasticity  of  the  metal.     The  price  of 

f  bronze  cannon  is  about  45  cents  per  pound. 
108.  steel.  This  substance  possesses,  in  a  higher  de- 
^gree  than  any  other,  the  important  qualities  of  tenacity 
and  hardness;  but  the  practical  difficulty  of  making  it 


140  CANNON. STEEL. 

in  masses  of  sufficient  size,  has  heretofore  prevented  it 
from  being  used  in  the  construction  of  heavy  cannon. 

Steel  is  a  compound  of  iron  and  carbon,  in  which  the 
proportion  of  the  latter  is  from  5  to  1  per  cent.,  and 
even  less,  in  some  kinds.  Steel  may  be  distinguished 
from  iron  by  its  fine  grain ;  its  susceptibility  of  harden- 
ing by  immersing  it,  when  hot,  in  cold  water ;  and  with 
certainty  by  the  action  of  diluted  nitric  acid,  which 
leaves  a  black  spot  on  steel,  and  on  iron  a  spot  which  is 
lighter  colored  in  proportion  as  the  iron  contains  less 
carbon. 

There  are  many  varieties  of  steel,  the  principal  of 
which  are : 

Natural  steel,  which  is  obtained  by  reducing  the  rich 
and  pure  kinds  of  iron  ore  with  charcoal,  and  refining 
the  cast  iron,  so  as  to  deprive  it  of  a  sufficient  portion  of 
carbon  to  bring  it  to  a  malleable  state.  It  is  made 
principally  in  Germany,  and  is  used  for  making  files 
and  other  tools. 

The  India  steel,  called  wootz,  is  said  to  be  a  natural 
steel,  containing  a  small  portion  of  other  metals. 

Blistered  steel,  or  steel  of  cementation,  is  prepared  by 
the  direct  combination  of  iron  and  carbon.  For  this 
purpose,  the  iron  in  bars  is  put  in  layers  alternating 
with  powdered  charcoal,  in  a  close  furnace,  and  exposed 
for  seven  or  eight  days  to  a  heat  of  about  10°  Wedge- 
wood,  and  then  sufikred  to  cool  for  as  many  days  more. 
The  bars,  on  being  taken  out,  are  covered  with  blisters, 
have  acquired  a  brittle  quality,  and  exhibit  in  the  frac- 
ture a  uniform  crystalline  appearance.  The  degree  of 
carbonization  is  varied  according  to  the  purposes  for 
which  the  steel  is  intended,  and  the  best  qualities  of 


KIND    OF    METALS. STEEL.  141 

iron  (Russian  and  Swedish)  are  used  for  the  finest  kinds 
of  steel. 

Tilted  steel  is  made  from  blistered  steel  moderately 
heated  and  subjected  to  the  action  of  a  tilt-hammer,  by 
which  means  its  tenacity  and  density  are  increased,  and 
it  is  thus  adapted  to  use. 

Shear  steel  is  made  from  blistered  or  natural  steel  re- 
fined by  piling  thin  bars  into  fagots,  which  are  brought 
to  a  welding  heat  in  a  reverberatory  furnace,  and  ham- 
mered or  rolled  again  into  bars.  This  operation  is 
repeated  several  times  to  produce  the  finest  kinds  of 
shear  steel,  which  are  distinguished  by  the  names  of 
half  shear,  single  shear,  and  double  shear,  or  steel  of  1 
mark,  of  2  marks,  of  3  marks,  &c,  according  to  the 
number  of  times  it  has  been  piled. 

Cast  steel  is  made  by  breaking  blistered  steel  into 
small  pieces  and  melting  it  in  close  crucibles,  from  which 
it  is  poured  into  iron  moulds ;  the  ingot  is  then  reduced 
to  a  bar  by  hammering  or  rolling,  as  described  under 
the  head  of  malleable  iron,  these  operations  being  per- 
formed with  great  care.  Cast  steel  is  the  finest  kind  of 
steel,  and  best  adapted  for  most  purposes :  it  is  known 
by  a  very  fine,  even,  and  close  grain,  and  a  silvery,  homo- 
geneous fracture ;  it  is  very  brittle,  and  acquires  extreme 
hardness,  but  it  is  difficult  to  weld  without  the  use  of  a 
flux.  The  other  kinds  of  steel  have  a  similar  appear- 
ance to  cast  steel,  but  the  grain  is  coarser  and  less  ho- 
mogeneous ;  they  are  softer  and  less  brittle,  and  weld 
more  readily.  A  fibrous  or  lamellar  appearance  in  the 
fracture  indicates  an  imperfect  steel.  A  material  of 
great  toughness  and  elasticity,  as  well  as  hardness,  is 
made  by  forging  together  steel  and  iron,  forming  the 


142  CANNON. STEEL. 

celebrated  damask-steel,  which  is  used  for  sword-blades, 
springs,  etc. ;  the  damasked  appearance  is  produced  by 
the  action  of  a  diluted  acid,  which  gives  a  black  tint  to 
the  steel  parts,  whilst  the  iron  remains  white. 

Various  fancy  steels,  or  alloys  of  steel  with  silver, 
platinum,  rhodium,  and  aluminum,  have  been  made 
with  a  view  to  imitating  the  Damascus  steel,  wootz, 
etc.,  and  improving  the  fabrication  of  some  of  the  finer 
kinds  of  surgical  and  other  instruments. 

Properties  of  steel.  The  best  steel  possesses  the  fol- 
lowing characteristics :  heated  to  redness  and  plunged 
into  cold  water,  it  becomes  hard  enough  to  scratch  glass 
and  to  resist  the  best  files ;  the  hardness  is  uniform 
throughout  the  piece;  after  being  tempered  it  is  not 
easily  broken;  it  welds  readily;  it  does  not  crack  or 
split ;  it  bears  a  very  high  heat,  and  preserves  the  capa- 
bility of  hardening  after  repeated  working ;  the  grain 
is  fine,  even,  and  homogeneous,  and  it  receives  a  bril- 
liant polish.  Its  specific  gravity  is  7.816,  being  greater 
than  that  of  iron. 

109.  Puddled  §teei.  If,  in  the  operation  of  puddling, 
or  decarbonizing  cast  iron,  the  process  be  stopped  at  a 
particular  time,  determined  by  indications  given  by  the 
metal  to  an  experienced  eye,  an  iron  is  obtained  of 
greater  hardness  and  strength  than  ordinary  iron,  to 
which  the  name  of  semi-steel,  or  puddled  steel,  has  been 
applied.  The  principal  difficulty  in  its  manufacture  is 
that  of  obtaining  uniformity  in  the  product,  homogeneity 
and  solidity  throughout  the  entire  mass.  It  is  much 
improved  by  reheating  and  hammering  under  a  heavy 
hammer. 

A  tenacity  of  118,000  lbs.  to  the  square  inch  has  been 


KIND    OF    METALS. WROUGHT    IRON.  143 

obtained  from  semi-steel  made  in  this  country  in  this 
way.  Field-pieces  have  been  made  of  this  material,  but, 
thus  far,  they  have  not  been  found  to  possess  uniform 
strength  and  endurance. 

110.  Wrought  iron.  This  material  was-  among  the 
earliest  employed  in  the  construction  of  cannon ;  but,  in 
consequence  of  the  defects  which  almost  invariably  ac- 
company the  forging  of  large  masses,  it  was  superseded 
by  bronze  and  cast  iron.  Notwithstanding  that  most 
authorities  unite  in  stating  that  this  change  was  con- 
sidered, at  the  time,  a  great  improvement,  frequent  at- 
tempts have  been  made  to  revive  the  use  of  wrought 
iron,  and  especially  within  the  last  two  years,  but  with- 
out success. 

Tensile  strength.  The  tensile  strength  of  wrought 
iron,  which,  under  the  most  favorable  circumstances,  is 
double  that  of  the  best  cast  iron,  depends  on  the  charac- 
ter of  the  crystalline  structure,  and  the  manner  of  ap- 
plying the  tensile  force ;  or,  in  other  words,  wrought 
iron  offers  the  greatest  resistance  to  a  force  of  extension, 
when  the  structure  is  fibrous  and  the  force  acts  in  the 
direction  of  the  fibres.  From  experiments  made  to  de- 
termine the  elastic  limits,  and  tensile  strength  with 
reference  to  the  direction  of  the  fibre,  Mallet  makes  this 
important  deduction :  that  for  artillery  purposes,  the 
ultimate  strength  of  a  fire-arm  in  which  the  explosive 
strains  are  all  resisted  by  wrought  iron  in  the  direction 
of  the  fibre,  is  to  the  resistance  in  a  transverse  direction 
as  234.80  is  to  30.47,  or  H  to  1. 

But  the  practical  difficulties  of  rapidly  cooling  large 
masses,  so  as  to  form  small  crystals,  and  compressing 
them  by  hammering,  rolling,  or  otherwise,  to  develop 


144  CANNON. MATERIALS. 

and  give  a  particular  direction  to  the  fibre,  have  not 
thus  far  been  wholly  surmounted  by  the  most  liberal 
expenditure  of  money  and  mechanical  skill.*  On  the 
contrary,  large  masses  are  generally  found  to  contain 
such  internal  defects  as  false  welds,  cracks,  and  a  spongy 
and  irregularly  crystalline  structure,  arising  from  the 
more  rapid  cooling  of  the  exterior  surface. 

From  careful  trials  made  with  the  material  of  the 
large  wrought-iron  gun  which  burst  with  such  fatal 
results  on  the  steamer  Princeton  a  few  years  ago,  it 
was  ascertained  that  it  had  lost  one-sixth  of  its  original 
strength  in  the  process  of  manufacture,  and  the  texture 
of  the  fragments  varied  from  fine  granular  to  coarse 
crystalline. 

Hardness,  &c.  Wrought  iron  is  softer  than  cast  iron, 
and  being  pure  iron,  is  more  liable  to  be  corroded  by 
the  action  of  the  atmosphere,  and  products  of  combus- 
tion of  the  powder. 

Ductility.  It  possesses  considerable  ductility,  or 
extension  beyond  the  elastic  limit,  as  was  shown  by 
experiments  made  on  the  iron  used  in  the  Prince- 
ton's gun.  A  bar  0.6  inch  diameter  was  stretched  so 
much  that  its  diameter  was  reduced  to  0.5  before  rup- 
ture. 

111.  Ca§t  iron.  This  metal  is  now  very  generally 
employed  in  the  fabrication  of  heavy  cannon  for  siege 
and  sea-coast  purposes.     It  possesses  the  very  important 

*  Wrought-iron  cannon  for  field  service  are  now  being  successfully  made  by  the 
Phoenix  Iron  Company,  near  Philadelphia.  Briefly,  the  process  consists  in  forming 
a  bundle  of  iron  bars  in  such  manner  that  the  heat  may  permeate  the  mass,  and 
bring  the  different  parts  to  the  welding  point  at  the  same  time,  and  then  passing 
it  through  grooved  rollers  until  it  is  thoroughly  welded.  To  give  a  proper  direction 
to  the  fibre,  the  inner  bars  are  placed  in  a  longitudinal  direction,  and  the  outer  ones 
are  wrapped  in  a  spiral  direction  around  them. 


CAUSES    WHICH    AFFECT    ITS    QUALITY. TESTING.    145 

qualities  of  tenacity,  hardness,  and  cheapness,  and  with 
proper  care  is  not  seriously  affected  by  rust.  Its  prin- 
cipal defect  is  an  almost  entire  want  of  elasticity,  in 
consequence  of  which  its  tenacity  is  destroyed  after  a 
certain  number  of  applications  of  the  straining  force, 
depending  on  the  relation  which  this  force  bears  to  the 
tensile  strength  of  the  iron  itself. 

Causes  which  affect  its  quality.  Cast  iron  is  a  well 
known  compound  of  iron  and  carbon.  The  amount  of 
carbon,  the  state  of  its  combination,  together  with  the 
ore,  fuel,  and  fluxes,  and  the  process  of  manufacture, 
materially  affect  the  quality  of  cast  iron  for  artillery 
purposes. 

Many  experiments  have  been  made  by  the  ordnance 
department  in  the  last  few  years,  to  ascertain,  by  chem- 
ical and  mechanical  means,  the  precise  causes  which  im- 
prove or  injure  the  quality  of  cast  iron  ;  but  with  little 
success.  The  utmost  that  has  been  accomplished,  is  the 
knowledge  that  certain  ores,  treated  in  a  certain  way, 
make  cast  iron  suitable  for  cannon  ;  but  the  reasons  for 
such  results  are  but  little  understood. 

A  slight  variation  in  the  ore — even  when  taken  from 
the  same  deposit — in  the  fuel,  in  the  model  of  the  piece, 
or  in  the  character  of  the  powder,  has  been  known  to 
produce  the  most  disastrous  results. 

How  tested.  The  fitness  of  a  particular  kind  of  cast 
iron  for  cannon-metal,  can  only  be  determined  by  sub- 
mitting it  to  the  tests  of  the  service  ;  after  this  is  known, 
a  knowledge  of  certain  physical  properties,  such  as 
tenacity,  hardness,  density,  and  color,  form  and  size  of 

crystals,  presented  in  a  freshly-fractured  surface,  will  be 
10 


146  CANNON. M  ATERI ALS. 

useful  in  keeping  the  metal  up  to  the  required  standard, 
and  securing  its  presence  in  the  finished  piece. 

The  course,  recently  adopted  in  both  land  and  naval 
services,  is  to  leave  the  selection  of  the  metal  to  the 
private  founders,  and  to  require  that  one  gun  out  of  a 
certain  number  shall  be  selected,  and  proved  in  the 
ordinary  way,  and  afterward  fired  continuously  1,000 
service-rounds.  If  the  result  be  satisfactory,  it  is  re- 
quired that  all  other  guns  shall  be  made  precisely  like 
it ;  and  it  is  made  the  duty  of  officers  on  foundry  ser- 
vice, to  see  that  this  condition  is  strictly  complied  with. 

Ores.  Pig,  or  cast  iron,  is  generally  known  by  the 
name  of  the  blast-furnace  in  which  it  is  made.  The 
ores  at  ^present  used  by  the  U.  S.  government  for  the 
manufacture  of  cannon,  are  the  Cloverdale  in  Virginia, 
Bloomfield  in  Pennsylvania,  and  the  Greenwood,  near 
West  Point,  N.  Y.  Many  other  ores  have  been  tried, 
but  none  have  thus  far  been  found  to  answer  so  well  as 
these.    /<•<{-    ^~*~?  A\***t     fl^g^ 

Character  of  pig-iron.  Ores  suitable  for  "  gun-metaV 
should  be  reduced  in  the  smelting  furnace,  with  char- 
coal and  the  warm  blast*  Iron  thus  made,  or  pig-iron 
should  be  soft,  yielding  easily  to  the  file  and  chisel ;  the 
appearance  of  the  fracture  should  be  uniform,  with  a 
brilliant  aspect,  dark  gray  color,  and  medium-sized 
crystals. 

Character  of  gun  metal.  When  remelted  and  cast  into 
cannon,  it  should  approach  that  degree  of  hardness 
which  resists  the  file  and  chisel,  but  not  so  hard  as  to  be 
bored  and  turned  with  much  difficulty.  Its  color  should 
be  a  bright,  lively  gray ;  crystals  small,  with  acute  an- 

*  Varying  from  125°    to  300°,  Fahr.,  depending  upon  the  ore  used. 


GENERAL    PROPERTIES    OF    CAST   IRON.  147 

gles,  and  sharp  to  the  touch ;  structure  uniform,  close, 
and  compact. 

If  pig-iron  be  too  soft,  coarse,  and  loose,  its  strength 
and  density  may  be  increased  by  remelting  it  once  or 
twice,  and  by  allowing  it  to  remain  in  a  state  of  fusion, 
subjected  to  a  high  degree  of  heat. 

The  density  of  pig-iron  is  about  7.00  and  its  tenacity 
about  16.000  pounds  to  the  square  inch.  The  density 
of  gun-metal,  or  remelted  pig,  is  about  7.250,  and  its 
tenacity  about  30.000 — nearly  double  the  former. 

General  properties  of  cast  iron.  There  are  several 
varieties  of  cast  iron,  differing  from  each  other  by  al- 
most insensible  shades ;  the  principal  divisions  are  gray 
and  white,  called  so  from  the  color  of  the  fracture  when 
recent. 

Gray  iron  is  softer  and  less  brittle  than  white  iron ; 
it  is  in  a  slight  degree  malleable  and  flexible ;  and  is 
not  sonorous ;  it  can  be  easily  drilled  and  turned  in  the 
lathe,  and  does  not  resist  the  file.  It  has  a  brilliant 
fracture,  of  a  gray,  or  sometimes  bluish-gray  color ;  the 
color  is  lighter  as  the  grain  becomes  closer,  and  its  hard- 
ness increases  at  the  same  time.  A  medium-sized  grain, 
bright-gray  color,  lively  aspect,  fracture  sharp  to  the 
touch,  and  close,  compact  texture,  indicate  a  good  quali- 
ty of  iron.  A  grain  either  very  large  or  very  small,  a 
dull,  earthy  aspect,  loose  texture,  dissimilar  crystals 
mixed  together,  indicate  an  inferior  quality. 

Gray  iron  melts  at  a  lower  temperature  than  white 
iron,  becomes  more  fluid,  and  preserves  its  fluidity 
longer ;  it  runs  smoothly ;  the  color  of  the  metal  is  red, 
and  deeper  in  proportion  as  the  heat  is  lower;  it  does 
not  stick  to  the  ladle ;  it  fills  the  mould  well ;  contracts 


148  '     •      ,  CANNON. MATEEIALS. 

less ;  and  contains  fewer  cavities  than  white  iron ;  the 
edges  of  a  casting  are  sharp,  and  the  surface  smooth, 
convex,  and  covered  with  carburet  of  iron.  Gray  iron 
is  the  only  kind  suitable  for  making  castings  which 
require  great  strength,  such  as  cannon.  Its  tenacity 
and  specific  gravity  are  diminished  by  slow  cooling  or 
annealing. 

White  iron  is  very  brittle  and  sonorous ;  it  resists 
the  file  and  the  chisel,  aud  is  susceptible  of  high  polish ; 
the  surface  of  the  casting  is  concave;  the  fracture  pre- 
sents a  silvery  appearance,  generally  fine-grained  and 
compact,  sometimes  radiating,  or  lamellar.  Its  qualities 
are  the  reverse  of  those  of  gray  iron ;  it  is  therefore 
unsuitable  for  ordnance  purposes.  Its  tenacity  is  in- 
creased, and  its  specific  gravity  diminished  by  annealing. 
Its  mean  specific  gravity  is  7.500,  while  that  of  gray 
iron  is  only  7.200. 

Mottled  iron  is  a  mixture  of  white  and  gray  ;  it  has  a 
spotted  appearance — hence  its  name ;  it  flows  well,  and 
with  few  sparks ;  the  casting  has  a  plane  surface,  with 
edges  slightly  rounded.  It  is  suitable  for  making  shot 
and  shells. 

Besides  these  general  divisions,  the  manufacturers  dis- 
tinguish more  particularly  the  different  varieties  of  pig- 
metal  by  numbers,  from  1  to  6,  according  to  their  relative 
hardness. 

The  qualities  of  these  various  kinds  of  iron  would 
seem  to  depend  on  the  proportion  of  carbon  and  the 
state  in  which  it  is  found  in  the  metal.  In  the  darker 
kinds  of  iron,  where  the  proportion  is  sometimes  7  per 
cent,  of  carbon,  it  exists  partly  in  the  state  of  graphite, 
or  plumbago,  which  makes  the  iron  soft.     In  white  iron, 


COMBINED    METALS.  149 

the  carbon  is  thoroughly  combined  with  the  metal,  as  in 
steel. 

Cast  iron  frequently  retains  a  portion  of  foreign  in- 
gredients from  the  ore,  such  as  earths,  or  oxides  of  other 
metals,  and  sometimes  sulphur  and  phosphorus,  which 
are  all  injurious  to  its  quality.  Sulphur  hardens  the 
iron,  and  unless  in  very  small  proportions,  destroys  its 
tenacity.  These  foreign  substances,  and  also  a  portion 
of  the  carbon,  are  separated  by  melting  the  iron  in  con- 
tact with  air ;  and  soft  iron  is  thus  rendered  harder  and 
stronger. 

All  cast  iron  expands  forcibly  at  the  moment  of  be- 
coming solid,  and  again  contracts  in  cooling ;  gray  iron, 
as  before  remarked,  expands  more,  and  contracts  less, 
than  other  iron — an  important  fact  in  considering  the 
effect  of  unequal  cooling. 

The  color  and  texture  of  cast  iron  depend  greatly  on 
the  size  of  the  casting  and  the  rapidity  of  cooling :  a 
small  casting,  which  cools  quickly,  is  almost  always 
white ;  and  the  surface  of  large  castings  partakes  more 
of  the  qualities  of  white  metal  than  the  interior. 

112.  Combined  metai§.  Numerous  trials  have  been 
made  to  improve  the  strength  of  cannon,  by  combining 
two  or  more  metals  in  such  a  way  that  the  good  quali- 
ties of  one  shall  counteract  the  defects  of  the  others. 
For  instance,  it  has  been  sought  to  increase  the  hard- 
ness of  bronze  cannon  by  casting  the  metal  around  a 
core  of  cast  or  wrought  iron;  and  to  increase  the 
strength  of  cast-iron  cannon  by  enveloping  them  in 
hoops  of  wrought  iron,  "  shrunk  on"  in  the  process  of 
cooling. 

The  principal  objections,  in  theory,  to  such  combina- 


150  CANNON. MATERIALS. 

tions  arise  from  the  unequal  tensile,  expansile,  and  elas- 
tic properties  of  the  different  metals,  and  the  want  of 
strength  and  solidity  in  the  union  of  the  different  parts. 

Armstrong  and  Mallet.  The  most  noted  instances  of 
"  built-up"  cannon  of  the  present  day,  are  Armstrong's 
Rifle  Gun,  and  Mallet's  Monster  Mortar.  The  former  is 
made  by  wrapping  strips  of  wrought  iron  spirally  around 
a  tube  of  the  same  material,  which  constitutes  the  sides 
of  the  bore.  The  strip  of  each  layer  is  welded  together 
at  its  edges,  and  it  runs  in  a  crosswise  direction  to  that 
of  the  layer  which  precedes  it.  This  method  makes  a 
very  strong  but  a  very  expensive  gun. 

The  latter  is  formed  of  three  compound  wrought-iron 
rings,  or  cylinders,  placed  one  upon  the  other,  so  as  to 
constitute  the  chase  and  reinforce  of  the  piece.  The 
breech  is  made  by  embedding  the  wrought-iron  chamber 
in  a  large  mass  of  cast  iron,  and  the  chase  and  reinforce 
are  fastened  to  it  by  longitudinal  rods  running  along 
the  outside  of  the  piece. 

The  bore  of  this  mortar  was  36  inches  diameter,  and 
the  bursting  charge  of  the  shell  was  480  lbs.  of  powder. 
Although  it  was  tried  with  only  one-half  the  intended 
charge,  it  proved  deficient  in  strength. 

Treadwell.  Professor  Treadwell,  of  Cambridge,  Mass., 
who  has  had  considerable  experience  in  the  manufacture 
of  steel  and  wrought-iron  cannon,  proposes  a  veryj  inge- 
nious plan  of  making  cannon  of  cast  and  wrought  iron.* 
The  core  of  the  piece  is  formed  of  a  tube  of  cast  iron, 

*  The  Parrott  rifle  gun,  at  present  extensively  used  in  our  field  service,  is  a  light 
cast-iron  gun,  strengthened  by  shrinking  a  band  of  wrought  iron  around  that  part 
of  the  gun  which  surrounds  the  seat  of  the  charge.  The  pieces  of  this  kind  now  in 
use  are  the  10-pdr.  and  20-pdr.  A  30-pdr.  for  siege  and  a  100-pdr.  for  sea-coast 
service  have  also  been  prepared. 


TO    DETERMINE    PRESSURE.  151 

the  thickness  of  which  is  about  one-half  of  the  thickness 
of  an  ordinary  cannon.  This  he  considers  sufficient  to 
resist  the  pressure  of  the  charge  on  the  bottom  of  the 
bore.  The  core  is  then  surrounded  by  successive  layers 
of  wrought-iron  hoops,  each  u  shrunk  on"  with  a  pres- 
sure proportional  to  the  square  of  its  distance  from  the 
centre,  in  order  that  all  may  be  brought  to  the  point 
of  rupture  at  the  same  instant,  if  necessary. 

EXTEKIOK  FORM. 

113.  Thickness  of  metal.  The  exterior  form  of  can- 
non is  determined  by  the  variable  thickness  of  the  metal 
which  surrounds  the  bore  at  different  points  of  its 
length.  In  general  terms,  the  thickness  is  greatest  at 
the  seat  of  the  charge,  and  least  at  or  near  the  muzzle. 
This  arrangement  is  made  on  account  of  the  variable 
action  of  the  powder  and  projectile  along  the  bore,  and 
the  necessity  of  disposing  the  metal  in  the  safest  and 
most  economical  manner,  or,  in  other  words,  to  propor- 
tion it  according  to  the  strain  it  is  required  to  bear. 

114.  To  determine  the  pressure  by  calculation.  It  has 
been  proposed  to  determine  the  pressure  of  the  powder 
at  the  different  points  of  the  bore,  by  supposing  all  the 
gases  evolved  in  the  first  moment  of  combustion,  and, 
as  the  space  behind  the  projectile  increased,  applying 
Mariotte's  law,  that  the  tension  of  gas  is  proportional 
to  its  density,  which,  in  turn,  is  inversely  proportional 
to  the  space  passed  over  by  the  projectile.  This  method 
of  determining  the  pressure  gives  a  very  rapid  taper  to 
the  exterior ;  and  however  well  it  may  answer  for  cast- 
iron  cannon,  is  unsuitable  for  those  made  of  bronze ; 


152  CANNON. EXTERIOR    FORM. 

which  are  found,  in  practice,  to  burst  in  the  chase,  in  con- 
sequence of  the  enlargement  of  the  bore  from  the  striking 
of  the  projectile  against  its  sides. 

A  more  correct  method  of  calculating  the  pressure  is 
to  apply  the  principles  laid  down  in  Chap.  I. 

In  the  case  of  a  French  12-pdr.  field  gun,  which  is 
fired  with  a  charge  of  £  the  weight  of  the  projectile,  the 
formulas  show  that  the  projectile  is  moved  1.9  in.  when 
the  gases  have  reached  their  maximum  density  of  0.38, 
water  being  taken  as  unity. 

Substituting  this  value  in  Rumford's  formula,  it  will 
be  found  that  the  mean  pressure  of  the  charge,  on  the 
surrounding  surface,  is  1,500  atmospheres ;  and  with 
powder  made  by  the  English,  or  "  rolling-mill"  process, 
the  mean  pressure  is  found  to  be  as  high  as  2,400  atmos- 
pheres. The  pressure  at  other  points  may  be  deter- 
mined in  a  like  manner. 

115.  Determination  of  pressure  by  experiment.  About 
the  year  1841,  Colonel  Bomford  devised  a  plan  for  de- 
termining the  pressure  at  various  points  of  the  bore  by 
direct  experiment.  It  essentially  consists  in  boring  a 
series  of  small  holes  through  the  side  of  a  gun,  at  right 
angles  to  its  axis  (see  fig.  33),  the  first  hole  being  placed 
at  the  seat  of  the  charge,  and  the  others  at  intervals  of 
one  calibre.  A  steel  ball  was  projected  from  each  hole,  in 
succession,  into  a  target  or  ballistic  pendulum,  by  the 
force  of  the  charge  acting  through  it ;  and  the  pressures 
at  the  various  points  were  deduced  from  the  velocities 
communicated  to  the  balls ;  it  was  by  this  means  that  the 
form  of  the  columbiads  was  determined.  This  plan  has 
been  lately  tried  in  Prussia  with  great  care  and  success. 

Instead  of  the  projectile,  Captain  Rodman  uses  a  steel 


NATURE  OF  FORCE  TO  BE  RESTRAINED. 


153 


punch  which  is  pressed  by  the  force  of  the  charge  into 
a  piece  of  soft  copper.  The  weight  necessary  to  make 
an  equal  indentation  in  the  same  piece,  is  then  ascer- 
tained by  the  "  testing  machine,"  or  machine  employed 
to  determine  the  strength  of  cannon  materials.  This 
instrument  is  known  as  the  "pressure  piston,"  and  is 
used  in  proving  powder  to  measure  the  strain  which  is 
exerted  on  the  bore  of  the  eprouvette,  or  gun. 

The  following  diagram  shows  the  results  obtained  by 
this  apparatus  applied  to  a  42-pdr.  gun.* 


12 


1U  Calibers. 


8 

Fig.  33. 

116.  Nature  of  force  to  be  restrained.  In  estima- 
ting the  effect  of  any  force  upon  a  yielding  material  to 
which  it  may  be  applied,  the  rate  of  application,  or  the 
time  which  elapses  from  the  instant  when  the  force 
begins  to  act  until  it  attains  its  maximum,  should  not 
be  neglected ;  for,  with  equal  ultimate  pressures  per 
square  inch  of  surface,  that  powder  will  be  most  severe 

*  The  data  from  which  the  above  diagram  was  constructed,  were  taken  from 
experiments  made  by  Captain  Rodman,  to  compare  the  effect  of  hollow  cake-pow- 
der, with  the  ordinary  grained  powder. 

The  ordinates  of  the  curved,  show  the  pressures  on  the  bore  at  intervals  of  two 
calibres,  commencing  at  the  bottom  of  the  bore,  for  the  grain-powder ;  and  those  of 
the  curve  B  the  same  for  "  cake-powder."  The  gun  being  suspended  as  a  pendu- 
lum, and  the  recoil  being  equal,  or  nearly  so,  it  follows  that  nearly  the  same  velocity 


154 


CANNON. EXTERIOR   FORM. 


upon  the  gun  which  attains  this  pressure  in  the  shortest 
period  of  time  after  ignition.  The  smaller  the  grain 
the  more  rapid  will  be  the  combustion  of  any  charge 
of  powder  (other  things  being  equal),  and  hence  the 
greater  will  be  the  strain  on  the  gun  in  which  it  is 
burned.* 

117.  Various  kinds  of  strain.  The  strains  to  which  all 
fire-arms  are  subjected,  are  four  in  number,  viz. : 

1st.  The  tangential  strain,  which  acts  to  split  the 
piece  open  longitudinally,  and  is  similar  in  its  action  to 
the  force  which  bursts  the  hoops  of  a  barrel. 

2d.  The  longitudinal  strain,  which  acts  to  pull  the 
piece  apart  in  the  direction  of  its  length.  Its  action  is 
the  greatest  at  or  near  the  bottom  of  the  bore,  and  least 
at  the  muzzle,  where  it  is  nothing. 

These  two  strains  increase  the  volume  of  the  metal  to 
which  they  are  applied. 

3d.  A  strain  of  compression,  which  acts  from  the  axis 

was  communicated  to  the  projectile  by  the  •*  cake"  as  by  the  grain  powder,  with 
only  about  one-half  the  mean  pressure  on  the  length  of  the  bore. 


Caked  Powder. 

Grained  Powder. 

No. 

Distance  from 

of 

bottom  of 

Pressure, 

Pressure, 

fires 

the  bore. 

per  square  inch. 

Kecoil. 

Eecoil. 

per  square  inch. 

3 

0 

10.989 

22° 

24' 

22° 

58' 

41.289 

3 

2  Calibres. 

26.001 

24° 

21' 

22° 

56' 

57.512 

3 

4 

12.457 

22° 

57' 

22° 

59' 

14.103 

3 

6 

8.620 

25o 

43' 

23° 

05' 

10.878 

3 

8 

5.801 

24° 

12' 

22° 

53' 

10.417 

3 

10 

4.870 

21° 

43' 

22° 

49' 

7.127 

3 

12 

4.071 

22° 

07' 

22° 

55' 

8.932 

3 

14         " 

4.071 

21° 

42' 

22° 

49' 

9.007 

*  Eeport  of  Experiments,  by  Captain  Rodman,  to  Colonel  of  Ordnance. 


KINDS    OF   STRAIN. 


155 


outward,  to  crush  the  truncated  wedges  of  which  a  unit 
of  length  of  the  piece  may  be  supposed  to  consist,  and 
to  give  a  cross-section  the  shape  shown  in  the  diagram 
(fig.  A).  This  strain 
compresses  the  metal  and 
enlarges  the  bore.  If  the 
metal  were  incompressi- 
ble, the  appearance  of  a 
cross-section  of  the  rup- 
ture would  be  that  of  fig.  B ;  and  no  enlargement  of 
the  bore  would  result  from  the  crushing  of  the  metal ; 
and  any  enlargement  of  the  bore  caused  by  the  action  of 
the  tangential  force,  would  be  accompanied  by  an  equal 
enlargement  of  the  exterior  diameter  of  the  piece  ;  and 
hence  the  strain  upon  the  metal,  at  the  inner  and  outer 
surfaces  of  the  gun,  would  be  inversely  as  the  radii  of 
these  surfaces,  instead  of  inversely  as  their  squares  (as 
in  the  case  of  a  compressible  material).  This  quality 
would  bring  into  action  one-third  more  tangential  re- 
sistance than  the  same  metal  would  be  capable  of  offer- 
ing to  a  central  force. 

4th.  A  transverse  strain,  which  acts  to  break  trans- 
versely, by  bending  outward  the  staves  of  which  the 
piece  may  be  supposed  to 


consist.  This  strain  com- 
presses the  metal  on  the 
inner,  and  extends  it  on 
the  outer  surface.  The 
resistance  which  a  bar  of  iron,  supported  at  its  extrem- 
ities, will  offer  to  a  pressure  uniformly  distributed  over 
it,  is  directly  as  the  square  of  its  depth,  and  inversely 
as  the  square  of  its  length ;  and  this  is  the  same  as  the 


156  CANNON. EXTERIOR    FORM. 

resistance  offered  by  a  stave  of  the  piece  when  support- 
ed at  the  points  d  and  b. 

If  p  be  the  pressure  on  a  unit  of  surface  of  the  bore, 
and  s  the  tensile  strength  of  the  metal,  it  can  be  shown 
by  analysis,  that  the  tendency  to  rupture,  or  the  pres- 
sure on  a  unit  of  length  of  the  bore,  divided  by  the 
resistance  which  the  sides  are  capable  of  offering  to 
rupture,  for  a  piece  of  one  calibre  thickness  of  metal, 
will  be  as  follows,  viz. : 

Tangential,  3E; 

or,  rupture  will  take  place  when  three  times  the  pres- 
sure is  greater  than  twice  the  tensile  strength. 

Longitudinal,  £-\ 

or,  rupture  will  take  place  in  the  direction  of  the  length 
when  the  pressure  is  greater  than  twice  the  tensile 
strength. 

Transverse,  ^2;  % 

7  3s' 

or,  rupture  will  take  place  when  twice  the  pressure  is 
greater  than  three  times  the  tensile  strength. 

From  the  above  it  appears,  that  the  tendency  to  rup- 
ture is  greater  from  the  action  of  the  tangential  force 
than  for  any  other ;  and  for  lengths  above  two,  or  per- 
haps three,  calibres,  "the  tangential  resistance  may  be 
said  to  act  alone,  as  the  aid  derived  from  the  transverse 
resistance  will  be  but  trifling,  for  greater  lengths  of 
bore  or  stave;  but  for  lengths  of  bore  less  than  two 
calibres,  this  resistance  will  be  aided  by  both  the  trans- 
verse and  the  longitudinal  resistance.  Every  piece 
should,  therefore,  have  sufficient  thickness  of  breech  to 


DIVISION    OF   THE   EXTEEIOE.  157 

cause  rupture  to  take  place  (if  at  all)  along  the  lines, 
b  c  and  d  e  (fig.  35),  instead  of  splitting  through  the 
breech ;  and  after  this  point  has  been  attained,  any  ad- 
ditional thickness  of  breech  adds  nothing  to  the  strength 
of  the  piece. 

From  the  foregoing,  we  conclude  that  a  fire-arm  is 
strongest  at  or  near  the  bottom  of  the  bore,  and  that 
its  strength  is  diminished  rapidly  as  the  length  of  the 
bore  increases,  to  a  certain  point  (probably  not  more 
than  three  calibres  from  the  bottom);  after  which,  for 
equal  thicknesses  of  metal,  its  strength  becomes  sen- 
sibly uniform. 

/  118.  Division  of  the  exterior.*   The  exterior  of  a  can- 
'  l  nbn  is  generally  divided  into  five  principal  parts,  viz. : 
the  breech,  the  1st  reinforce,  the  2d  reinforce,  the  chase, 
and  the  swell  of  the  muzzle.     See  fig.  26. 

The  breech.  The  breech,  or  thickness  of  metal  in  the 
prolongation  of  the  axis  of  the  bore,  should  be  at  least 
equal  to  1-]-  times  the  diameter  of  the  bore.  A  thick- 
ness of  one  diameter  has  been  found  insufficient  for 
heavy  iron  guns. 

First  reinforce.    This  part  extends  from  the  base-ring 

*  The  following  formula,  which  is  used  for  calculating  the  exterior  form  of  can- 
non of  large  calibre  for  the  land  service,  was  deduced  by  Captain  Rodman  from  a 
series  of  original  experiments  on  the  strength  of  hollow  cylinders,  &c. : 

C-- ^—  X 


S        ~  (R— r)  (2  r  L  +  R  (R  +  r)  (R— r)    V 


V) 


in  which  C  is  a  constant  quantity,  r  =  interior  radius,  and  R  =  exterior  radius,  p  =*= 
pressure  of  gas,  1=  length  of  bore  pressed,  required  to  fully  develop  transverse 
resistance,  L=  length  of  bore  corresponding  to  assumed  values  of  R,  S= tensile 
strength  of  metal,  and  1'  =  length  of  bore  subjected  to  maximum  pressure.  The 
pressure  of  the  gas  is  supposed  to  vary  inversely  as  the  square  root  of  the  length  of 
the  bore  behind  the  projectile.  The  exterior  forms  thus  obtained  are  entirely  made 
up  of  curved  lines,  and  a  specimen  of  them  is  seen  in  fig.  46,  which  represents  that 
of  the  new  columbiads. 


UNIVERS! 


158  CANNON. EXTERIOR    FORM. 

to  the  seat  of  the  ball,  and  is  the  thickest  part  of 
the  piece,  for  the  reason  that  the  pressure  of  the 
powder  is  found,  both  by  experiment  and  calculation, 
to  be  greatest  before  the  projectile  is  moved  far  from 
its  place.  The  shape  of  this  reinforce  was  formerly 
made  slightly  conical,  under  the  impression  that  the 
pressure  was  greater  at  the  vent  than  at  the  seat  of 
the  projectile ;  but  it  is  now  made  cylindrical  through- 
out. For  bronze  cannon,  the  thickness  of  this  part 
is  approximately  given  by  the    empirical  formula  in 


fcW3. 


E=D\J  x"p>whh?h  D  represents  the  diameter  of  a 

solid  cast-iron  shot  suited  to  the  bore;  O  the  proof 
charge ;  and  P  the  real  weight  of  the  projectile.  For 
cast-iron  cannon,  E  should  be  multiplied  by  the  coeffi 
cient  1.17.  In  general  terms,  the  thickness  of  a  bronze 
gun,  at  the  seat  of  the  charge,  is  a  little  less,  and  of  a 
cast-iron  gun  a  little  greater,  than  the  diameter  of  the 
bore.  These  dimensions  exceed  those  determined  by 
calculation,  but  are  necessary  to  enable  the  piece  to 
resist  the  shocks  of  the  projectile,  &c. 

Second  reinforce.  This  portion  of  the  piece  connects 
the  first  reinforce  with  the  chase.  It  is  made  considera- 
bly thicker  than  necessary  to  resist  the  pressure  of  the 
powder,  in  order  to  serve  as  a  proper  point  of  support  for 
the  trunnions,  and  to  compensate  for  certain  defects  of 
metal  liable  to  occur  in  the  vicinity  of  the  trunnions  of 
all  cast  cannon,  arising  from  the  crystalline  arrange- 
ment, and  unequal  cooling  of  the  different  parts. 

Chase.  From  the  extremity  of  the  second  reinforce, 
cannon  taper  more  or  less  rapidly  to  the  vicinity  of  the 


DIVISION    OF   THE    EXTERIOR.  159 

muzzle.  This  part  is  called  the  chase,  and  constitutes 
the  largest  portion  of  the  piece  in  front  of  the  trunnions. 
The  principal  injury  to  which  the  chase  is  liable,  arises 
from  the  striking  of  the  ball  against  the  side  of  the 
bore ;  and  the  thickness  of  metal  should  be  sufficient  to 
resist  it.  In  pieces  of  soft  iron,  or  bronze,  the  indenta- 
tions thus  made  by  the  projectile  may  increase  to  the 
extent  of  bursting  the  piece ;  but  in  cast-iron  cannon, 
where  they  never  exceed  0.02  inch,  the  taper  of  the 
chase  can  be  made  more  rapid,  or,  with  the  same  weight 
of  metal,  longer  than  in  bronze  guns.  An  example  of 
this  is  seen  in  the  Dahlgren  guns  of  the  naval  service. 

For  many  years,  cast-iron  cannon  have  been  made  in 
Sweden  of  a  form  nearly  approaching  that  called  for  by 
the  actual  pressure  of  the  powder  at  different  points  of 
the  bore.     See  fig.  36. 


V — = 


Fig.  36. 

In  the  construction  of  bronze  guns,  the  thickness  of 
the  metal  at  the  neck,  or  thinnest  part,  is  about  equal 
to  -f'T  of  that  at  the  first  reinforce,  or  T5TJE,  given  in  the 
empirical  formula  on  p.  158. 

Sivell  of  the  muzzle.  Inasmuch  as  the  metal  situated 
immediately  at  the  muzzle,  is  supported,  only  in  rear,  it 
has  been  usually  considered  necessary  to  increase  its 
thickness,  to  enable  it  to  resist  the  action  of  the  projec- 
tile at  this  point.  This  enlargement  is  called  the  swell 
of  the  muzzle.     At  present,  the  practice  is  to  reduce  the 


160  CANNON. EXTERIOR  FORM. 

diameter  of  the  swell  of  tlie  muzzle  of  all  cannon,  and 
particularly  that  of  heavy  iron  cannon,  designed  to  be 
fired  through  embrasures.  By  a  late  order  of  the  war 
department,  the  swell  is  to  be  hereafter  omitted  from 
all  sea-coast  cannon. 

In  field  and  siege  howitzers,  the  muzzle  band  takes 
the  place  of  the  swell. 

All  projections  on  the  surface  of  cannon,  not  abso- 
lutely necessary  for  the  service  of  the  piece,  are  omitted 
in  cannon  of  late  models.  This  omission  simplifies  their 
construction,  renders  them  easier  to  clean,  and  obviates 
certain  injurious  strains  that  would  otherwise  arise  from 
unequal  cooling  in  fabrication. 

119.  Trunnions.  The  trunnions  are  two  cylin- 
drical arms  attached  to  the  sides  of  a  cannon,  for  the 
purpose  of  supporting  it  on  its  carriage.  They  are 
placed  on  opposite  sides  of  the  piece,  with  their  axes  in 
the  same  line,  and  at  right  angles  to  its  axis. 

Size.  The  size  of  the  trunnions  depends  on  the  recoil 
of  the  piece,  and  the  material  of  which  they  are  made. 
The  resistance  which  a  cylinder  opposes  to  rupture,  is 
proportional  to  the  cube  of  its  diameter,  or  the  weight 
of  a  sphere  of  the  same  diameter.  On  the  supposition 
that  the  strain  is  proportional  to  the  weight  of  the 
charge,  it  is  laid  down  as  a  rule  that  the  diameter  of 
the  trunnions  of  guns  shall  be  equal  to  the  diameter  of 
the  bore,  and  the  diameter  of  the  trunnions  of  how- 
itzers shall  be  equal  to  the  diameter  of  their  cham- 
bers— the  recoil  being  less  than  for  guns  of  the  same 
calibre. 

Position.  The  position  of  the  trunnions,  with  refer- 
ence to  the  axis  of  the  bore,  influences  the  amount  of 


TKUNNIONS.  161 

recoil,  tlie  endurance  of  the  carriage,  and  the  extent  of 
the  vertical  field  of  fire. 

Fig.  37. 

By  reference  to  the  figure,  it  will  be  seen  that  if  the 
axis  of  the  trunnions  be  placed  below  the  axis  of  the 
piece,  the  resultant  of  the  force  of  the  charge,  which 
acts  against  the  bottom  of  the  bore,  will  act  to  turn  the 
piece  around  its  trunnion,  and  cause  the  breech  to  press 
upon  the  head  of  the  elevating  screw,  with  a  force  pro- 
portioned to  the  length  of  the  lever  arm,  or  distance  be- 
tween the  axes.  The  effect  will  be  to  press  the  trail  on 
the  ground  and  check  the  recoil — thereby  throwing  an 
additional  strain  on  the  carriage. 

If  the  trunnions  be  placed  above  the  axis  of  the 
piece,  rotation  will  take  place  in  the  opposite  direction, 
and  the  effects  of  the  discharge  on  the  carriage  and  re- 
coil will  be  reversed.  By  placing  the  two  axes  in  the 
same  plane,  the  force  of  the  charge  will  be  communi- 
cated directly  to  the  trunnions,  without  increasing  or 
diminishing  its  effect  on  the  carriage,  or  recoil;  this 
position  is  given  to  them  in  all  the  cannon  of  the  United 
States  service. 

It  is  evident  that  the  space  between  the  lower  side 
of  the  piece  and  the  carriage,  limits  the  amount  of  ele- 
vation or  depression  that  can  be  given  to  the  piece,  and 
that  the  greatest  angle  of  fire  can  be  attained  when  the 
axis  of  the  trunnions  is  situated  below  the  axis  of  the 
piece. 

120.  Preponderance.   The   unequal   distribution   of 
11 


162  CANNON. EXTERIOR    FORM. 

the  weight  of  a  piece  of  artillery,  with  reference  to  the 
axis  of  the  trunnions,  is  called  the  preponderance,  the 
object  of  which  is  to  give  it  stability  in  transportation 
and  firing,  by  producing  a  pressure  on  a  third  point  of 
support,  generally  the  head  of  the  elevating  screw.  In 
all  guns  and  howitzers,  the  centre  of  gravity  is  situated 
in  rear  of  the  trunnions,  and  in  all  mortars  it  is  situated 
in  front  of  them* 

Formerly  it  was  measured  by  the  weight  which  it 
was  necessary  to  apply  to  the  plane  of  the  muzzle  to 
balance  the  piece,  when  suspended  freely  at  the  axis  of 
the  trunnions ;  but  in  pieces  of  late  model  it  is  con- 
sidered equal  to  the  pressure  exerted  on  the  head  of 
the  elevating  screw,  or  a  third  point  of  support. 

The  position  of  the  trunnions,  with  reference  to  the 
length  of  the  piece,  is  an  important  consideration  in 
siege  and  sea-coast  cannon,  for  by  placing  them  further 
to  the  rear,  the  piece  can  be  elevated  and  depressed 
more  rapidly,  and  its  penetration  into  the  embrasure  is 
increased. 

121.  Rimba§es.  Rimbases  are  two  larger  cylinders 
(b  £),  placed  concentrically  around 
the  trunnions,  for  the  purpose  of 
strengthening  them  at  their  junc- 
tion with  the  piece,  and  by  form- 
ing shoulders,  to  prevent  the  piece 
from  moving  sideways  in  the  trun- 
Fig'  38'  nion-beds. 

*  The  mortars  and  eolumbiads  modelled  in  1861  have  no  preponderance,  as  the 
axis  of  the  trunnions  intersects  the  axis  of  the  piece  at  the  centre  of  gravity.  Cap- 
tain Rodman  has  shown  that,  contrary  to  the  generally-received  opinion,  cannon 
constructed  in  this  way  are  found  not  to  sensibly  change  their  position  before  the 
projectile  leaves  the  bore — and  that  the  accuracy  of  the  fire  is  not  affected. 


TRUNNIONS.  163 

122.  Knob  of  the  cascabie.  This  is  a  projection  affixed 
to  the  breech  of  a  cannon,  for  the  purpose  of  attaching 
the  sling  in  mounting  and  dismounting  it  from  its  car- 
riage.    Its  axis  is  that  of  the  bore  prolonged. 

123.  Handier  These  are  two  projections  (c  c,fig.  38,) 
placed  over  the  centre  of  gravity  of  certain  bronze  field- 
pieces,  for  manoeuvring  purposes. 

In  the  heavy  sea-coast  mortars,  the  handle  is  replaced 
by  a  clevis  attached  to  a  projection  cast  on  the  piece. 

124.  Portion  of  the  centre  of  gravity.  Having  deter- 
mined the  precise  form  of  each  part  of  a  cannon,  it  be- 
comes necessary  to  place  the  trunnions  so  that  the  breech 
shall  exert  a  given  pressure  on  the  head  of  the  elevating 
screw ;  or  in  other  words,  so  that  the  piece  shall  have  a 
certain  preponderance. 

In  making  the  computation,  it  will  be  necessary  to 
know  the  position  of  the  centre  of  gravity  of  the  piece ; 
and  this  may  be  determined  from  the  principle,  that  the 
sum  of  the  moments  of  the  weight  of  the  several  parts 
is  equal  to  the  moment  of  the  weight  of  the  entire  piece. 
For  convenience,  let  the  plane  of  reference  be  taken 
tangent  to  the  knob  of  the  cascabie,  and  at  right  angles 
to  its  axis. 

Let  a  be  the  volume  of  the  breech  and  cascabie, 
b         u  "  1st  reinforce, 

o        "  "  2d       " 

d        u  "  trunnions  and  rimbases, 

e        tt  "  chase, 

f  u  swell    of   muzzle    and 

mouldings, 
g  "  bore,     including     the 

chamber, 


164  CANNON. EXTERIOR    FORM. 

and  a' ,  b\  <fcc.,  the  distances  of  the  centre  of  gravity  of 
each  part  from  the  plane  of  reference,  respectively. 
Let  w  be  the  weight  of  a  unit  of  volume  of  the  piece, 
W  the  weight  of  the  piece,  and  x  the  distance  of  its 
centre  of  gravity  from  the  plane  of  reference. 

Taking  the  sum  of  the  moments  of  all  the  parts, 
diminishing  it  by  the  moment  of  the  bore,  and  placing 
the  remainder  equal  to  the  moment  of  the  piece,  we 
have  the  relation : 

(aa'+bb'+cc'+dd'+ee'+ff-gg')™ 
W 

Cancelling  the  unit  of  weight  in  the  numerator  and 
denominator  of  the  second  member  of  the  above  equa- 
tion, the  distance  of  the  centre  of  gravity  of  any  cannon, 
from  either  extremity,  is  equal  to  the  algebraic  sum  of 
the  products  of  the  volumes  of  the  parts  by  the  distances 
of  their  centres  of  gravity  from  that  extremity,  divided 
by  the  volume  of  the  metal. 

The  weight  of  the  piece  is  supported  by  the  elevat- 
ing screw  and  trunnions.  The  pressure  on  the  screw, 
and  its  distance  from  the  centre  of  gravity,  are  known ; 
and  the  distance  which  the  trunnions  should  be  placed 
in  front  of  the  centre  of  gravity,  to  support  the  re- 
mainder of  the  weight,  will  become  known  from  the 

proportion 

p  :  (  W—p)  ::y:l 

in  which  p  represents  the  preponderance,  I  the  distance 
of  the  head  of  the  elevating  screw  from  the  centre  of 
gravity,  (W—p)  the  weight  to  be  sustained  by  the 


WEIGHT    OF   CANNON.  165 

trunnions,  and  y  the  distance  of  their  axis  from  the 
centre  of  gravity. 

125.  Weight  of  cannon.  The  weight  of  a  cannon  is 
determined  by  the  weight  of  the  projectile,  the  maxi- 
mum velocity  it  may  be  necessary  to  communicate  to 
it,  and  the  extent  of  the  recoil. 

The  extent  of  the  recoil  being  limited  by  the  con- 
ditions of  the  service,  the  weight  of  the  piece  may 
be  deduced  from  the  principle,  that  action  and  reaction 
are  equal  and  opposite;  or,  that  the  quantity  of  motion 
expended  on  the  piece,  carriage,  and  friction,  is  equal 
to  that  expended  on  the  projectile,  and  the  air  set  in 
motion  by  the  charge. 

Let  w  be  the  weight  of  the  projectile, 
v  its  maximum  velocity, 
0  the  weight  of  the  charge  of  powder, 
N  a    constant    linear   quantity,  representing   the 
velocity    communicated   to    the   piece   by   a 
unit   of  the   charge,   arising  from   its  action 
on    the    air,    independent    of  the    projectile. 
For   American  powder,  this  has  been  found 
by  experiment    with    the   gun   and   ballistic 
pendulums,  to  be  equal  to   1,600  feet. 
/  the   velocity  lost  by  a  unit   of  mass,  from  the 
friction  of  the  carriage  on  ordinary  ground, 
W  the  weight  of  the  piece, 
V  velocity  of  recoil, 
0  the  weight  of  the  carriage, 
R  the  pressure  of  the  trail  on  the  ground,  arising 

from  the  recoil, 
g  the  force  of  gravity. 


166  CANNON. DIFFERENT    KINDS. 

From  the  principle  before  enunciated,  we  have 

g      9  g  9 

or,  by  reduction, 

w_wv+cN-  CV-  Cf-Bf 

For  field-guns,  the  velocity  of  the  recoil  should  not 
exceed  12  feet. 


DIFFERENT  KINDS  OF  CANNON. 

126.  Gun.  In  a  technical  sense,  a  gun  is  a  heavy 
cannon,  intended  to  throw  solid  shot  with  large  charges 
of  powder,  for  the  purpose  of  attaining  great  range,  ac- 
curacy, and  penetration. 

It  may  be  distinguished  from  other  cannon  by  its 
great  weight  and  length,  and  by  the  absence  of  a  cham- 
ber. 

The  gun  is  suited  to  fire  hollow  as  well  as  solid  pro- 
jectiles ;  and  the  only  limit  to  the  charge  is  the  strength 
of  the  projectile  to  resist  rupture  in  the  piece.  The  em- 
ployment of  shells  in  heavy  cannon,  after  the  manner 
of  solid  shot,  constitutes  the  basis  of  what  is  known  as 
General  Paixhan's  System  of  Artillery,  and  not  the  pe- 
culiar form  of  the  gun,  as  is  generally  supposed. 

The  calibre  of  a  gun  is  generally  expressed  in  terms 
of  the  weight  of  a  solid  cast-iron  ball  of  the  size  of  the 
bore. 

127.  Howitzer.  The  howitzer  is  a  cannon  employed 
to  throw  large   projectiles  with   comparatively  small 


RIFLED    CANNON.  167 

charges  of  powder.  It  is  shorter,  lighter,  and  more 
cylindrical  in  shape  than  a  gun  of  the  same  calibre ; 
and  it  has  a  chamber  for  the  reception  of  the  powder, 
generally  of  a  cylindrical  form. 

The  chief  advantage  of  a  howitzer  over  a  gun,  is, 
that  with  less  weight  of  piece,  it  can  produce  at  short 
ranges  a  greater  effect  with  hollow  projectiles  and  case 
shot.  It  also  affords  the  means  of  attaining  an  enemy 
sheltered  from  the  direct  fire  of  solid  shot. 

The  calibre  of  a  howitzer  may  be  expressed  in  terms 
of  the  weight  of  solid  shot,  as  in  guns ;  or  it  may  be 
expressed  in  terms  of  the  diameter  of  the  bore  in 
inches. 

128.  Ufortars.  A  mortar  is  a  short  and  comparative- 
ly light  cannon,  employed  to  throw  large,  hollow  projec- 
tiles, at  great  angles  of  elevation.  It  has  a  chamber, 
generally  of  a  conical  form,  and  of  a  size  suited  to  a 
small  charge  of  powder,  compared  to  the  weight  of  the 
projectile.  The  trunnions  of  all  mortars  are  attached 
to  the  breach  for  convenience  of  elevation  and  depres- 
sion.    (See  note  at  the  bottom  of  page  162.) 

Mortars  are  particularly  intended  to  produce  effect 
by  the  force  with  which  the  projectiles  descend  upon 
their  objects,  and  by  the  force  wdth  which  they  explode. 
They  are  employed  chiefly  against  inanimate  objects, 
such  as  the  roofs  of  buildings,  magazines,  and  case- 
mates, and  the  decks  of  ships  of  war. 

KIFLE-CANNON. 

129.  Definition.  A  rifle  is  a  fire-arm  which  has  cer- 
tain spiral  grooves  (or  "  rifles")  cut  into  the  surface  of 


168  CANNON. RIFLED. 

its  bore,  for  the  purpose  of  communicating  a  rotary 
motion  to  a  projectile  around  an  axis- coincident  with  its 
flight. 

The  object  of  this  rotation,  or  rifle-motion,  as  it  is 
generally  called,  is  to  increase  the  range  of  a  projectile, 
by  causing  it  to  move  through  the  air  in  the  direction 
of  its  least  resistance,  and  to  correct  the  cause  of  devia- 
tion, by  distributing  it  uniformly  around  the  line  of 
flight.  Rifle-motion  being  only  a  particular  case  of  the 
general  subject  of  rotation  of  projectiles,  its  peculiar 
effects  will  be  best  explained  and  understood,  in  a  sub- 
sequent chapter. 

130.  Rifles— how  clarified.  Military  rifles  maybe  di- 
vided into  rifle-cannon  and  rifle-muskets,  or  small  arms, 
which  only  differ  in  the  practical  application  of  the  rifle 
principle.  The  yielding  nature  of  lead  renders  the 
application  of  the  rifle  principle  of  easy  accomplishment 
in  the  case  of  rifle-muskets,  but  such  is  not  the  case  with 
rifle-cannon,  where  the  projectiles  are  made  of  iron. 

The  principal  question  which  now  occupies  the  atten- 
tion of  persons  engaged  in  improving  this  species  of 
cannon,  is  to  obtain  the  safest  and  surest  means  of  caus- 
ing the  projectile  to  follow  the  spiral  grooves  as  it 
passes  along  the  bore  of  a  rifled  piece.  Various  plans 
have  been  tried  to  attain  the  proposed  object,  some  of 
which  promise  to  be  successful.  Nearly  all  may  be 
ranged  under  the  following  heads,  viz. : 

1st.  Those  which  have  certain  flanges  or  projections 
on  the  projectile,  to  fit  into  the  grooves  of  the  gun  in 
loading.  This  plan  affords  certain  means  of  communi- 
cating the  rifle-motion,  but  it  has  not  been  found  a  safe 
one ;  probably,  from  the  wedging  of  the  flanges  in  the 


RIFLED    CANNON.  169 

grooves.  Besides,  the  dirt  from  the  burning  of  the  pow- 
der collects  in  the  grooves ;  and  as  it  is  difficult  to  clean 
them  by  the  usual  means,  the  projectile  is  liable  to  meet 
with  obstruction  in  loading. 

To  obviate  these  difficulties,  the  flanges  are  sometimes 
made  of  softer  metal  than  the  body  of  the  projectile,  as 
in  the  case  of  the  French  rifled  field-cannon.  Flanges 
that  fit  the  grooves  loosely  in  loading,  but  which  ex- 
pand when  the  piece  is  fired,  so  as  to  fit  them  tightly, 
have  been  tried  with  some  success. 

2d.  Those  cannon  in  which  the  form  of  the  bore  is  a 
twisted  prism,  with  an  elliptical  or  polygonal  base.  If 
the  metal  of  the  projectile  be  unyielding,  its  form  must 
be  similar  to  that  of  the  bore.  If  it  be  an  expanding 
projectile,  its  form  may  be  slightly  different  from  that  of 
the  bore. 

The  hexagonal  bore  is  one  of  the  best  for  communi- 
cating the  rifle-motion  to  a  projectile,  as  was  shown  by 
the  experiments  of  Mr.  Whitworth,  in  England ;  but  the 
experiments  made  with  this  form  of  bore  in  this  country, 
would  indicate  that  it  is  not  a  safe  one  for  ordinary  cast- 
iron  cannon. 

The  elliptical  bore,  as  tried  in  the  Lancaster  cannon, 
did  not  meet  with  the  success  anticipated  for  it. 

3d.  Those  cannon  in  which  the  projectile  is  con- 
structed on  an  expanding  principle.  The  body  of  an 
expanding  projectile  is  generally  made  of  cast  iron;  and 
the  expanding  portion  is  a  band,  or  cup  of  some  softer 
metal,  as  pewter,  copper,  wrought  iron,  or  papier-mache, 
&c.  which  enters  the  bore  freely  when  the  piece  is  loaded, 
but  which  is  forced  into  the  grooves  by  the  discharge. 
Projectiles  of  this  class  are  generally  as  easily  loaded  as 


170  CANNON. KIFLED. 

ordinary  projectiles,  and  if  properly  constructed,  do  not 
overstrain  the  piece. 

The  principal  objections  to  an  expanding,  or  compound 
projectile,  are  its  want  of  strength  to  resist  a  charge  of 
powder,  proportionately  as  large  as  that  employed  for 
a  simple  projectile,  and  the  danger  of  its  breaking  and 
wedging  in  the  bore  of  the  piece. 

The  projectile  adopted  for  the  United  States  land  ser- 
vice was  devised  by  Major  Dyer,  of  the  ordnance  de- 
partment, in  1857.  It  belongs  to  the  ex- 
panding class,  and  is  composed  of  a  cast- 
iron  body  (a),  and  an  expanding  cup  of 
soft  metal  (V),  which  is  formed  of  an  alloy 
of  lead  and  antimony. 

The  cup  and  body  are  firmly  united  in 
the  process  of  casting  by  covering  the 
surface  of  contact   with  tin.     The   dis- 
charge forces  the  sides  of  the  cup  into 
Mg.  39.  the   grooves,  and  thereby  compels  the 

projectile  to  take  up  the  rifle  motion. 

4th.  This  head  embraces  those  projectiles  which  are 
inserted  into  the  bore  through  an  opening  in  the  breech 
of  the  piece,  and  receive  their  rotary  motion  by  passing 
through  a  bore,  the  diameter  of  which  is  slightly  less 
than  that  of  the  projectile.  This  peculiar  operation,  of 
forcing  the  projectile  into  the  grooves  of  the  bore,  is 
technically  called  slugging,  and  can  only  be  applied  to 
projectiles  made,  wholly  or  partially,  of  a  yielding 
metal* 

The  breech-loading  principle  secures  for  the  projectile 

*  For  a  general  description  of  the  other  more  prominent  projectiles  used  in  the 
United  States,  see  appendix. 


UNIFORM    GROOVE.  lYl 

the  required  rifle-motion  with  great  certainty,  and  affords 
increased  facilities  for  loading  cannon  designed  to  be 
fired  through  an  embrasure ;  but  it  is  not  generally  con- 
sidered a  safe  principle  to  apply  to  large  cannon  made 
of  cast  iron  in  the  usual  way. 

131.  Form  of  groove.  The  form  of  a  rifle  groove  is 
determined  by  the  angle  which  the  tangent  at  any  point 
makes  with  the  corresponding  element  of  the  bore.  If 
the  angles  be  equal  at  all  points,  the  groove  is  said  to 
be  uniform.  If  they  increase  from  the  breech  to  the 
muzzle,  the  grooves  are  called  increasing,  if  the  reverse, 
decreasing  grooves. 

Twist  is  the  term  generally  used  by  gun-makers,  to 
express  the  inclination  of  a  groove  at  any  point,  and  is 
measured  by  the  length  of  a  cylinder  corresponding  to  a 
single  revolution  of  the  spiral ;  this,  however,  does  not 
convey  a  correct  idea  of  the  inclination  of  a  groove.  A 
correct  measure  of  the  inclination  of  a  rifle  groove  at 
any  point,  is  the  tangent  of  the  angle  which  it  makes 
with  the  axis  of  the  bore ;  and  this  is  always  equal  to 
the  circumference  of  the  bore  divided  by  the  length  of  a 
single  revolution  of  the  spiral,  measured  in  the  direction 
of  the  axis. 

132.  Uniform  groove.  To  construct  the  development 
of  a  uniform  groove,  let  A  B  be  the  base 
of  a  rectangle,  equal  to  the  circumference 
of  the  bore ;  B  C,  the  height  equal  to  the 
length  of  a  single  revolution  of  the  spiral, 
measured  on  the  axis  of  the  bore.  The 
diagonal  A  O  is  the  development  of  an 
entire  revolution  of  the  required  groove. 

Fig.  40.         On  the  line  A  D  lay  off  the  distance 


172  CANNON. KIFLED. 

A  d,  equal  to  the  length  of  the  bore ;  at  d  erect  a 
perpendicular,  and  the  line  A  c  will  be  that  portion 
of  the  development  of  the  groove  which  lies  on  the 
surface  of  the  bore. 

133.  Variable  groove.  Variable  grooves  are  con- 
structed by  wrapping  a  curve  around  the  surface  of  the 
bore.  The  curve  generally  selected  for  this  purpose,  is 
the  arc  of  a  circle. 

To  construct  the  development  of  an  increasing  groove 
which  shall  be  the  arc  of  a  circle :  The  known  condi- 
tions of  construction  are  the  length  of  the  bore,  and  the 
inclination,  or  twist,  at  the  breech  and  at  the  muzzle. 
The  quantity  to  be  determined  is  the  radius  of  the  gen- 
erating circle. 

Suppose  the  problem  solved,  and  let  B  P  represent 
the  element  of  the  bore  passing  through  the  extremity 

of  the  groove  at  the  muz- 
zle; P  C,  the  tangent  to 
the  groove  at  this  point; 
A  the  starting  point  of  the 
curve ;  and  A  J)  the  tangent 
Fig.  41.  to  the  groove  at  this  point. 

The  angle  of  the  tangent  and  element  at  the  breech,  is 
generally  made  zero,  and  is  so  considered  in  this  par- 
ticular case.  The  perpendiculars  at  A  and  P  are  radii 
of  the  required  circle,  and  their  intersection,  Oy  will  be 
its  centre. 

To  determine  the  length  of  the  radius  A  O,  and  the 
versed  sine  of  the  arc   A  P:     From  the   nature  of 

a   circle,  the   angle    CPB=AOP;    BO=      ^5,       • 
'  5  ;  tan.  BOP' 

and  OP=i/BP2+B02;    or,  by  substituting  for  BO 


METHOD    OF    CUTTING   GROOVES.  173 

its     value,     OP— \         BP2-\ irrrrrr*  and  AB— 

V  tan.2 CPB 


BP2  BP 


ttm.2CPB    ttm.BOP 


134.  Method  of  cutting  groove§.  The  practical  method 
of  cutting  grooves  in  cannon  is  essentially  the  same  as 
in  small  arms.  It  consists  in  moving  a  rod,  armed  with 
a  cutter,  back  and  forth  in  the  bore,  and  at  the  same 
time  revolving  it  around  its  axis.  If  the  velocities  of 
translation  and  rotation  be  both  uniform,  the  grooves 
will  have  a  uniform  twist ;  if  one  of  the  velocities  be  vari- 
able, the  grooves  will  be  either  increasing  or  decreasing, 
depending  on  the  relative  velocities  in  the  two  directions. 

135.  Comparative  advantages  The  comparative  ad- 
vantages of  uniform  and  variable  grooves,  depend  on 
the  means  used  to  connect  them  with  the  projectiles. 
If  the  bearing  of  the  projectile  in  the  grooves  be  long, 
and  the  metal  of  which  it  is  made  be  unyielding,  it  will 
be  unsafe,  if  not  impracticable,  to  employ  variable 
grooves ;  and  if  the  metal  be  partially  yielding,  a  portion 
of  the  force  of  the  charge  will  be  expended  in  changing 
the  form  of  that  part  of  the  projectile  which  projects 
into   the  grooves,  as  it  moves  along  the  bore. 

When  the  portion  in  the  grooves  is  so  short  that  its 
form  will  undergo  but  slight  alteration,  the  increasing 
groove  may  be  used  with  advantage,  as  it  diminishes 
the  friction  of  the  projectile  when  it  is  first  set  in 
motion,  and  thereby  relieves  the  breech  of  the  piece  of 
a  portion  of  the  enormous  strain  which  is  thrown  upon 
it.  If  the  twist  be  too  rapid  toward  the  muzzle,  there 
will  be  danger  of  bursting  the  piece  in  the  chase. 


174  CANNON. RIFLED. 

It  is  claimed  by  some,  that  the  variable  groove  is 
well  adapted  to  expanding  projectiles  with  short  bear- 
ing surfaces ;  but  the  uniform  groove,  being  more  sim- 
ple in  its  construction,  and  nearly  as  accurate  in  its 
results,  is  generally  preferred  for  military  fire-arms,  both 
large  and  small. 

136.  Number,  width,  and  §hape  of  grooves.  The 
width  of  a  groove  depends  on  the  diameter  of  the  bore, 
and  the  peculiar  manner  in  which  the  groove  receives 
and  holds  the  projectile. 

Wide  and  shallow  grooves  are  more  easily  filled  by 
the  expanding  portion  of  a  projectile  than  those  which 
are  narrow  and  deep  ;  and  the  same  holds  true  of  cir- 
cular-shaped grooves,  when  compared  to  those  of  angu- 
lar form.  An  increase  in  the  number  of  grooves  in- 
creases the  firmness  with  which  a  projectile  is  held,  by 
adding  to  the  number  of  points  which  bear  upon  it. 

It  has  been  suggested  that  rifle-cannon,  intended  for 
flanged  projectiles,  should  have  four  grooves;  as  a 
greater  number  increases  the  difficulties  of  loading,  and 
a  lesser  number  does  not  hold  the  projectile  with  suffi- 
cient steadiness. 

For  expanding  projectiles,  an  odd  number  of  grooves 
is  generally  employed,  for,  as  this  places  a  groove  op- 
posite to  a  land,  less  expansion  will  be  required  to 
fill  them.  The  number  of  grooves  used  in  the  3-inch 
field-gun  is  seven,  and  the  number  used  in  4i-inch  siege- 
guns  is  nine.  The  number  of  grooves  in  the  4-inch  Arm- 
strong gun  isjlfty. 

137.  Initial  velocity  of  rotation.  Let  l^be  the  ini- 
tial velocity  of  the  projectile,  or  space  which  it  would 
pass  over  in   one   second,  in   the   direction   of  flight, 


INCLINATION    OF    GROOVES.  175 

moving  with  the  velocity  with  which  it  leaves  the 
piece,  and  I  the  distance  passed  over  by  the  projectile 

in   making    one    revolution ;   therefore,  -=-  will  be  the 

number  of  revolutions   in   one  second,  and  27r—   the 

angular  velocity  of  the  projectile  at  the  muzzle.  The 
velocity  of  rotation  of  a  point  on  the  surface  is  given 
by  the  expression, 

o      V 
I 

in  which  r  is  its  distance  from  the  axis  of  motion,  and 
w  is  the  angular  velocity. 

138.  Inclination  of  grooves.  The  object  of  rifle- 
grooves  being  to  communicate  an  effective  rotary  motion 
to  a  projectile  throughout  its  flight,  it  remains  to  de- 
termine what  velocity  of  rotation,  or  inclination  of 
grooves,  is  necessary  for  different  projectiles. 

The  velocity  of  rotation  will  depend  on  the  form  and 
initial  velocity  of  the  projectile,  the  causes  which  re- 
tard it,  and  the  time  of  flight ;  therefore,  there  is  a  par- 
ticular inclination  of  grooves  which  is  best  suited  to  each 
calibre,  form  of  projectile,  charge  of  powder,  and  angle 
of  fire. 

It  is  proposed  to  investigate  the  effect  of  the  length 
and  calibre  of  the  projectile,  on  the  inclination  of  the 
grooves. 

139.  Effect  of  length.  It  has  been  noticed  that  if  very 
long  projectiles  be  fired  from  the  rifle-musket,  they  are 
less  accurate  than  the  ordinary  projectile,  the  length  of 
which  is  less  than  two  calibres.  Mr.  Whitworth  states 
that  he  has  known  a  bullet  twice  this  length,  turn  over 


176  CANNON. RIFLED. 

end  for  end,  within  six  feet  of  the  muzzle  of  the  Eng- 
lish rifle-musket,  the  calibre  of  which  is  nearly  the  same 
as  that  of  the  American  rifle-musket. 

This  instability  undoubtedly  arises  from  the  want  of 
sufficient  rotation  around  the  long  axis.  What  increase 
of  angular  velocity  must,  therefore,  be  given  to  com- 
pensate for  a  given  increase  of  length  of  an  oblong 
projectile? 

The  resistance  which  a  projectile  offers  to  angular 
deflection,  when  rotating  around  a  principal  axis,  is  pro- 
portional to  the  moment  of  its  quantity  of  motion  taken 
with  reference  to  this  axis,  or 

MWw, 
M  being  the  mass,  Jo  radius  of  gyration,  and  w  the  an- 
gular velocity. 

Let  this  expression  represent  the  moment  of  the 
quantity  of  motion  around  the  long  axis,  and  Tct  and  w/ 
the  radius  of  gyration,  and  angular  velocity,  around  a 
short  axis,  and  suppose  the  angular  velocities  w  and  w/ 
to  be  such  that  the  resistance  to  a  deflection  from  the 
axes  shall  be  equal,  we  have 

Mt?w=Mh2w„ 
and  by  reduction, 

W 

Hence,  if  we  determine  by  experiment  the  value  of  w, 
the  angular  velocity  necessary  to  give  practicable  sta- 
bility of  rotation,  we  can  determine  the  value  of  w„ 
and  consequently  the  superior  limit  of  the  deflecting 
forces. 

Substituting  the  value  of  w/  in  a  similar  expression 
for  any  other  projectile,  we  can  determine  the  angular 


EFFECT    OF    RESISTANCE   OF   THE   AIR.  177 

velocity,  and  from  this  the  inclination  of  grooves  neces- 
sary to  give  the  second  projectile  steadiness  in  flight. 

The  foregoing  method  of  determining  the  relation 
between  the  lengths  of  two  rifle-projectiles,  and  the  in- 
clination of  grooves  necessary  to  give  them  equal  stead- 
iness of  flight,  is  true  only  under  the  supposition  that 
they  preserve  throughout  their  range  the  relative  an- 
gular velocities  with  which  they  started.  It  is  neces- 
sary, therefore,  to  consider  the  causes  which  affect  ro- 
tation. 

140.  Effect  of  resistance  of  the  air.  The  cause  which 
retards  the  rotary  motion  of  a  rifle-projectile,  is  the 
friction  of  the  air  on  its  surface ;  and  its  retarding  effect 
will  be  equal  to  its  moment  divided  by  the  moment  of 
the  projectile's  quantity  of  motion. 

Let  f  be  the  friction  on  a  unit  of  surface  ;  »%  the  sur- 
face of  the  projectile  ;  p,  the  distance  of  the  resultant 
moment  of  the  friction  from  the  axis  of  motion ;  Jc,  the 
radius  of  gyration  ;  and  v,  the  mean  velocity  of  the  pro- 
jectile during  its  flight.  The  pressure  of  the  air  on  the 
projectile  is  nearly  proportional  to  the  square  of  its  velo- 
city :  f  $  v2  will  therefore  represent  the  friction  on  the 
projectile,  and/  s  v2  p  will  be  its  moment. 

The  moment  of  the  quantity  of  motion  of  the  pro- 
jectile is  Mk2w,  M  being  the  mass,  and  w  the  angular 
velocity. 

The  expression  for  the  angular  retardation  is,  there- 
fore, 

f$v2p 

MwW' 

To  find  the  angular  velocity  that  it  is  necessary  to 
give  to  another  projectile,  that  it  may  experience  the 

12 


178  CANNON. RIFLED. 

same  retarding  effect,  place  this  expression  equal  to  a 
similar  one,  answering  to  this  projectile,  and  we  have  : 

fsv2p  __fs/v2p/ 

Reducing,  and  recollecting  that  the  surface  is  propor- 
tional to  the  square,  and  the  mass  to  the  cube  of  the 
mean  diameter,  we  have : 

v2p  _     v2p,  # 
dWw~  d)c?w] 
or, 

v2p      v2p. 

in  '  ?/;   •  • —   *  

•     '"  aw  '  dthy 

Hence,  if  the  angular  velocity  necessary  for  one  rifle- 
projectile  be  known,  the  angular  velocity  necessary  for 
another  of  similar  form  and  material,  but  of  different 
size,  may  be  determined  by  calculation. 

Suppose  the  two  projectiles  to  be  round  shot,  and 
moving  with  the  same  mean  velocity,  through  the  same 
extent  of  trajectory,  the  proportion  reduces  to 

But  the  angular  velocity  is  inversely  proportional  to 

the  length  of  the  twist ;  it  follows,  therefore,  that  the 

"  length  of  twisf  of  grooves,  for  round  shot,  moving 

through  equal  lengths  of  trajectory,  and  with  equal  mean 

velocities,  should   be  directly   as  the   squares   of  their 

diameters. 

141.      Po§ition  of  centre  of  gravity.     The  further  the 

centre  of  gravity  of  a  projectile  is  in  rear  of  the  cen- 
tre of  figure,  or  resistance  of  the  air,  the  greater  will  be 
the  levqr  arm  of  the  deviating  force,  and,  consequently, 
the  greater  must  be  the  inclination  of  the  grooves,  to 


INCLINATION    OF    GKOOVES.  179 

resist  deviation.  A  conical  projectile,  of  the  same  length 
and  diameter,  requires  a  greater  inclination  of  grooves 
than  a  cylindrical  projectile ;  and  the  same  will  hold 
true  of  other  forms,  as  they  approach  one  or  the  other  of 
these  extreme  cases. 

142.  Limit  of  inclination.  The  friction  of  the  pro- 
jectile as  it  passes  along  the  grooves,  increases  with  their 
inclination ;  its  effect  will  be  to  diminish  the  range,  and 
increase  the  strain  on  the  piece.  It  is  easily  to  be  seen 
that  the  inclination  may  be  carried  so  far  as  to  break 
the  projectile,  or  rupture  the  piece. 

143.  Mo§t  §uitabie  inclination.  The  inclination  of 
grooves  for  a  rifle-cannon,  best  suited  to  a  given  projec- 
tile, has  not  yet  been  determined  by  experience ;  and 
the  consequence  is,  that  a  wide  diversity  of  "  twists"  is 
employed  in  different  services,  and  by  different  experi- 
menters. Colonel  Cavalli,  in  his  experiments  in  Sweden, 
obtained  good  results  from  twists  of  one  turn  in  12  feet, 
and  one  turn  in  35  feet,  in  a  32-pdr.  gun ;  and  a  still 
greater  variety  of  twists  have  been  employed  in  our  own 
service. 

For  a  projectile  one  and  a  half  diameters  long,  and 
6-pdr.  calibre,  excellent  practice  has  been  obtained  with 
a  twist  of  25  feet;  and  in  a  certain  form  of  the  Arm- 
strong gun,  the  twist  is  12  feet  for  a  bore  4  inches  in 
diameter. 

The  twist  of  the  new  wrought-iron  rifle-gun  for  field 
service,  is  10  feet,  and  the  twist  of  the  new  siege  gun 
is  15  feet.  The  calibre  of  the  former  is  3  inches,  and 
the  latter  4£  inches. 


180  CANNON. VAKIOUS    USES    OF. 


USES    TO  WHICH    CANNON  ARE    APPLIED. 

Having  discussed  the  general  principles  which  govern 
the  construction  of  all  cannon,  it  is  now  proposed  to 
consider  the  peculiarities  which  arise  from  the  uses  to 
which  the  several  kinds  are  applied. 

144.  Field-cannon.  Field-cannon  are  intended  to  be 
used  in  the  operations  of  an  army  in  the  field;  they 
should,  therefore,  have  the  essential  quality  of  mobility. 
They  are  divided  into  light  and  heavy  pieces.  The 
former  are  constructed  to  follow  the  rapid  movements 
of  light  troops  and  cavalry.  The  latter  are  employed 
to  follow  the  movements  of  heavy  troops,  to  commence 
an  action  at  long  distance,  to  defend  field-works  and 
important  positions  on  the  field  of  battle,  &c. ;  hence 
they  are  said  to  constitute  "  batteries  of  position." 

The  light  pieces  are  the  6-pdr.  gun  and  12-pdr.  how- 
itzer. The  heavy  pieces  are  the  12-pdr.  gun,  24-pdr.  and 
32-pdr.  howitzers. 

The  detailed  dimensions,  &c,  of  all  cannon  for  the 
United  States,  land  service,  may  be  ascertained  by  refer- 
ence to  the  Ordnance  Manual ;  but,  in  order  that  the 
pupil  may  form  a  correct  general  idea  of  them,  a  few  of 
the  most  important  data  will  be  given  under  each  head ; 
and,  to  assist  the  memory,  they  will,  as  far  as  practica- 
ble, be  expressed  in  terms  of  the  calibre. 

Weight  The  weight  of  field-guns  is  about  150,  and 
howitzers,  100  times  that  of  their  projectiles. 

Length  of  bore.  As  field-cannon  are  seldom  used  to 
fire  through  embrasures,  and  as  lightness  is  an  indis- 
pensable requisite,  the  length  of  the  bore  is  confined 


FIELD    CANNON.  181 

to  the  shortest  effective  length  for  each  kind  and  calibre. 
For  guns,  it  is  about  16,  and  for  howitzers,  about  10 
diameters. 

Natural  angle  of  sight  The  natural  angle  of  sight 
is  1°. 

Material.  In  Sweden,  field-cannon  are  made  of  cast 
iron;  in  all  other  countries,  of  bronze.  In  1840,  cast- 
iron  field-cannon  of  American  pattern,  were  made  at  one 
of  the  most  celebrated  foundries  in  Sweden,  brought  to 
this  country,  and  subjected  to  extreme  proof,  by  the  side 
of  similar  cannon  made  of  American  cast  iron.  The 
result  showed  that  American  gun-iron  was  not  inferior 
to  the  Swedish;  and  it  is  the  opinion  of  experienced 
persons,  that  suitable  field-cannon  can  be  made  of  cast 
iron.  The  small  size,  however,  of  these  pieces,  and  the 
absence  of  entire  confidence  in  this  material,  have  prob- 
ably induced  the  proper  authorities  to  adhere  to  bronze 
as  a  material  for  all  field-cannon. 

Charge.  The  charges  of  powder  for  field  service,  in 
terms  of  the  solid  shot,  are, 

For  Guns. 
Solid  shot,  shells,  and  spherical  case,  one-fifth. 
Canister  shot,  one-sixth. 

For  Howitzers. 
Shells  and  case-shot,  one-twelfth. 

Vertical  field  of  fire.  The  vertical  field  of  fire  is  20°: 
12°  above,  and  8°  below  the  horizon. 

The  foregoing  are  some  of  the  most  important  points 
in  the  system  of  field  cannon  adopted  in  1840  ;  many 
of  the  pieces  of  which  are  still  in  service. 


182  CANNON. VARIOUS    USES    OF. 

145.  The  new  field  or  Napoleon  gun.  In  1856  it  was 
proposed  to  increase  the  power  of  the  light  and  dimin- 
ish the  weight  of  the  heavy  field-artillery,  by  the  intro- 
duction of  a  single  piece  of  medium  weight  and  calibre, 
(see  par.  76). 


Fig.  42. 

Form.  The  form  of  the  new  piece  is  shown  in 
fig.  42.  It  has  no  chamber,  and  should  therefore  be 
classed  as  a  gun.  Its  exterior  is  characterized  by  the 
entire  absence  of  moulding  and  ornament ;  and  in  this 
respect  it  may  be  at  once  distinguished  from  the  old 
field-cannon.  The  first  reinforce  is  cylindrical ;  and  it 
has  no  second  reinforce,  as  the  exterior  tapers  uniformly 
with  the  chase  from  the  extremity  of  the  first  reinforce. 
The  size  of  the  trunnions  and  the  distance  between  the 
rimbases  are  the  same  as  in  the  24-pdr.  howitzer,  in 
order  that  both  pieces  may  be  transported  on  the  same 
kind  of  carriage* 

Dimensions,  &c.  The  diameter  of  the  bore  is  that  of 
a  12-pdr.  The  length  of  bore  is  16  calibres.  The  weight 
is  100  times  the  projectile,  or  1,200  lbs.  The  charge  of 
powder  is  the  same  as  for  the  heavy  12-pdrs.  (pattern 
of  1840),  or  2^  lbs.  for  solid  and  case  shot,  and  2  lbs. 
for  canister  shot.      It  has,  therefore,  nearly  as  great 

*  The  new  rifle-gun  adopted  for  the  field  service  is  made  of  wrought  iron,  and 
modelled  after  the  plan  of  Captain  Rodman.  Its  weight  is  820  lbs.,  and  the  diam- 
eter of  the  bore  is  3  inches.  The  weight  of  the  projectile  is  about  10  lbs.,  and  the 
charge  of  powder  is  1  lb.     The  length  of  the  bcre  is  21  66  diameters. 


MOUNTAIN  AND    PRAIRIE    CANNON.  183 

range  and  accuracy  as  the  heaviest  gun  of  the  old  sys- 
tem ;  and,  at  the  same  time,  the  recoil  and  strain  on  the 
carriage  are  not  too  severe. 

The  new  gun  and  carriage  weigh  about  500  lbs.  more 
than  the  6-pdr.  and  carriage ;  still,  it  has  been  found  to 
possess  sufficient  mobility  for  the  general  purposes  of 
light  artillery.  It  is  proposed  to  retain  the  12-pdr. 
howitzer  in  service,  to  be  employed  in  cases  where  great 
celerity  of  movement  is  indispensable. 

The  effect  of  this  change  is  to  simplify  the  materiel  of 
field  artillery,  and  to  increase  its  ability  to  cope  with 
the  rifle-musket,  principally  by  the  use  of  larger  and 
more  powerful  spherical  case-shot.  The  principal  ob- 
jection to  an  increased  calibrl  for  light  field-guns,  is  the 
increased  weight  of  the  ammunition,  and  the  reduction 
of  the  number  of  rounds  that  can  be  carried  in  the  am- 
munition chests. 


MOUNTAIN  AND  PEAIEIE  CANNON. 

146.  Mountain  howitzer.  Mountain  artillery  is  de- 
signed to  operate  in  a  country  destitute  of  carriage-roads, 
and  inaccessible  to  field  artillery.  It  mustr  therefore,  be 
light  enough  to  be  carried  on  pack-animals. 

The  piece  used  for  moun- 
tain service  is  a  short,  light 
12-pdr.    howitzer,    weighing 
Fig.  43.  220   lbs.     See   fig.   43.     The 

form  of  the  chamber  is  cylindrical,  and  suited  to  a 
charge  of  £  lb.  of  powder.  The  projectiles  are  shells 
and  case-shot. 

It  is  discharged  from  a  low  two-wheel  carriage,  which 


184  CANNON. SIEGE   AND    GARRISON    CANNON. 

serves  for  transportation  whenever  the  ground  will  per- 
mit. When  the  piece  is  packed,  the  carriage  is  packed 
on  a  separate  animal. 

The  mountain  howitzer  is  also  employed  for  prairie 
service,  and  in  defending  camps  and  frontier  forts 
against  Indians,  in  which  case  it  is  mounted  on  a  light 
four-wheel  carriage,  called  "  the  prairie  carriage." 

In  the  Mexican  war,  the  mountain  howitzer  was  found 
useful,  from  the  facility  with  which  it  could  be  carried 
up  steep  ascents,  and  to  the  tops  of  flat-roofed  houses,  in 
street-fighting. 

SIEGE  AND   GARRISON   CANNON. 

Siege  cannon  are  intended  for  attacking,  and  gar- 
rison cannon  for  defending,  inland  fortifications  and 
the  land  fronts  of  sea-coast  fortifications. 

They  comprise  guns,  howitzers,  and  mortars. 

147.  Siege  guns.  A  siege  gun  is  constructed  to  throw 
a  solid  projectile  with  the  highest  practicable  velocity, 
in  order  to  penetrate  the  masonry  of  revetments,  and  to 
diminish  the  curvature  of  the  projectile's  flight,  thereby 
increasing  its  chances  of  hitting  objects  but  slightly 
raised  from  the  ground* 

Calibre.  Although  the  12-pdr.  siege  gun  has  been 
found  competent  to  breach  good  masonry,  large  calibres 
will  accomplish  the  object  in  a  shorter  time,  and  at  a 
greater  distance. 

The  calibre,  or  weight,  of  siege  guns  must  be  limited 

*  The  new  rifle  siege  gun  is  made  of  cast  iron,  modelled  after  the  new  plan. 
Its  weight  is  3,450  lbs.,  and  the  diameter  of  the  bore  is  4.5  inches.  The  length  of 
the  bore  is  26.66  diameters.  The  weight  of  the  projectile  is  about  34  lbs.,  and  the 
charge  varies  from  one-tenth  to  one-eighth  the  projectile. 


SIEGE   MORTARS.  185 

by  the  means  of  transporting  them  and  their  projectiles 
to  the  scene  of  action.  With  horse-power  over  ordinary 
roads,  the  24-pdr.  is  the  largest  that  can  be  employed 
with  convenience.  With  railroad  or  water  communica- 
tion, very  large  calibres  may  be  brought  into  action,  as 
was  the  case  at  Sebastopol,  where  the  English  troops 
used  the  68-pdr.  gun  for  breaching,  and  the  13-inch 
mortar  for  vertical  firing. 

The  siege  guns  are  the  12-pdr.,  18-pdr.,  and  24-pdr. 

Charge.  The  usual  charge  of  powder  for  breaching 
masonry,  is  \  the  weight  of  the  solid  shot  This  is  the 
greatest  that  can  be  fired  without  overstraining  the  gun 
and  its  carriage ;  and  besides,  as  the  resistance  of  the 
air  increases  nearly  with  the  square  of  the  velocity,  very 
little  additional  useful  effect  would  be  produced  on  the 
projectile  by  a  greater  charge.  The  usual  charge  for 
range  is  J-  the  weight  of  the  projectile. 

Length.  The  mean  length  of  bore  of  the  three  guns, 
is  20  diameters.  This  length  nearly  secures  the  full 
effect  of  the  powder,  and  causes  the  muzzle  to  project 
well  into  the  embrasure  of  the  battery,  thereby  pre- 
venting the  blast  from  injuring  its  cheeks. 

Weight  The  mean  weight  is  about  260  times  the 
weight  of  the  shot. 

Vertical  field  of  fire.  The  construction  of  the  car- 
riage permits  the  gun  to  be  elevated '12°,  and  depressed 
4°.     The  natural  angle  of  sight  is  1°  30'. 

Form.  The  form  of  siege  guns  is  similar  to  that 
shown  in  Hg.  26. 

In  the  French  service,  siege  cannon  are  made  of 
bronze ;  but  in  most  other  services,  including  our  own, 
they  are  made  of  cast  iron. 


186 


CANNON. SIEGE   AND   GARRISON    CANNON. 


148.  Siege  howitzer.  The  siege  howitzer  is  principally 
employed  for  ricochet  firing,  and  for  the  purpose  of  bat- 
tering down  the  earth  and  fragments  of  masonry  which 
are  left  standing  by  the  breaching-guns.* 

Dimensions,  &c.  Its  bore  is  8  inches  in  diameter,  and 
nearly  five  diameters  long,  and  it  has  a  cylindrical 
chamber  capable  of  holding  exactly  4  lbs.  of  powder. 
As  this  piece  is  sometimes  fired  over  the  heads  of  men 

in  the  advanced  trenches,  no 
sabot  or  cartridge-block  can  be 
placed  between  the  shell  and 
powder ;  hence,  the  surface  join- 
ing the  chamber  and  bore,  is 
made  spherical,  to  conform  to  the  projectile.  The  form 
of  this  piece  is  shown  in  fig.  44. 

Trunnions.  The  size  of  the  trunnions,  and  distance 
between  the  rimbases,  are  made  the  same  as  in  the  24- 
pdr.  gun,  in  order  that  it  may  fit  the  24-pdr.  carriage. 

Hecess.  The  preponderance  is  regulated  by  remov- 
ing a  portion  of  the  metal  which  surrounds  the  chamber. 
The  space  thus  left  is  called  the  recess. 

149.  Siege  mortar*.  The  siege  mortars  comprise  the 
common  mortar,  the  stone  mortar,  and  the  Coehorn  mor- 


Fig.  44. 


tar. 


Dimensions.  The  form  of  the  common  siege  mortars, 
is  shown  in  fig.  45.  There  are  two.  sizes, 
the  8-inch  and  10-inch,  called  so  from  the 
diameters  of  their  bores.  The  length  of 
the  bore  is  1^  diameters,  measured  from  the 
Fig.  45.        bottom  of  the  projectile.     The  chambers 


*  The  form  of  the  new  siege  howitzer  differs  from  the  old  one  in  having  a  per- 
fectly smooth  exterior.     The  chamber  is  elliptical  in  form. 


STONE-MORTAR.  187 

are  of  the  Gomer  form,  and  capable  of  holding  a  charge 
of  powder  j7  the  weight  of  the  projectile.* 

The  weight  of  the  piece  is  about  twenty  times  that  of 
the  shell. 

Vertical  field,  of  fire.  The  vertical  field  of  fire  lies 
between  30°  and  60° ;  45°  is  the  angle  at  which  all  mor- 
tars are  usually  fired,  as  this  gives  nearly  the  maximum 
range  for  a  given  charge  of  powder. 

Natural  line  of  sight.  The  exterior  form  of  siege 
mortars  is  cylindrical ;  consequently  the  natural  line  of 
sight  is  parallel  to  the  axis  of  the  bore — a  position  of 
great  convenience  in  aiming. 

Object.  Siege  mortars  are  used  to  attain  those  por- 
tions of  a  work,  by  a  vertical  fire,  which  are  defended 
against  the  direct  and  ricochet  fires  of  guns  and  howit- 
zers, such  as  the  covered  way,  the  ditch,  with  its  com- 
munications, and  the  roofs  of  magazines,  casemates,  <fcc. 

150.  stone  mortar.  The  stone  mortar  is  employed  in 
siege  operations  to  precipitate  a  large  mass  of  small 
stones,  or  hand-grenades,  upon  the  heads  of  the  enemy 
in  the  advanced  trenches,  or,  in  like  manner,  to  clear  the 
breach  of  its  defenders  preparatory  to  an  assault.f 

Dimensions,  &c.  The  diameter  of  the  bore  is  16  inches, 
and  its  length  is  about  \\  times  its  diameter.  Its  cham- 
ber is  conical,  and  the  charge  of  powder  for  120  lbs.  of 
stones  is  1^  lbs. ;  and  for  fifteen  6-pdr.  shells,  it  is  1  lb. 
It  is  made  of  bronze,  and  mounted  on  a  bed  similar 
to  that  for  the  10-inch  mortar. 

*  The  form  of  all  the  mortars  adopted  in  1861  is  shown  in  fig.  48.  The  chase  is 
cylindrical,  the  breech  is  hemispherical,  and  the  trunnions  are  placed  opposite  to 
the  centre  of  gravity.     The  chamber  is  elliptical  instead  of  the  Gomer  form. 

f  The  stone  mortar  has  been  left  out  of  the  list  of  new  cannon  for  the  United 
States,  service,  the  common  mortar  being  used  instead. 


188  CANNON. SEA-COAST   CANNON. 

Spherical  case-shot  for  mortars.  It  is  proposed  by 
some  military  writers,  to  dispense  with  the  stone  mortar 
in  siege  operations,  and  use,  in  its  place,  the  10-inch 
mortar,  with  spherical  case-shot ;  as  it  has  lately  been 
shown,  in  Belgium,  that  if  a  10-inch  mortar-shell  be 
filled  with  canister  balls,  1.5  inches  diameter,  and  be 
exploded  in  its  descent,  about  50  feet  from  the  ground, 
the  balls  will  have  sufficient  force  to  disable  men. 

151.  Coeiiorn  mortar.  The  Coehorn  mortar,  so  called 
after  its  inventor,  General  Coehorn,  is  a  very  small 
bronze  mortar,  designed  to  throw  a  24-pdr.  shell  to  dis- 
tances not  exceeding  1,200  yards.  Its  weight  is  164  lbs., 
its  maximum  charge  \  lb.  powder,  and  it  is  mounted 
on  a  wooden  block  furnished  with  handles,  so  that  two 
men  can  easily  carry  it  from  one  part  of  a  work  to 
another. 

SEA-COAST  CANNON. 

152.  Object.  Sea-coast  cannon  are  mounted  in  sea- 
coast  batteries  for  the  defence  of  harbors,  roadsteads, 
&c,  against  vessels  of  war.  Their  efficiency  depends  on 
size  of  calibre,  combined  with  facility  of  manoeuvre,  or 
rapidity  of  fire. 

As  these  cannon  generally  occupy  permanent  posi- 
tions, the  weight  of  the  piece  is  not  so  serious  an  objec- 
tion to  an  increase  of  calibre,  as  the  weight  of  the  pro- 
jectile, which,  if  too  great,  renders  the  loading  slow 
and  the  fire  less  effective.  It  is  found  that  shells  of  10 
or  11  inches  diameter  are  quite  as  heavy  as  two  men  can 
conveniently  lift  to  the  muzzle  of  the  piece.  The  8-in. 
calibre  is  thought  by  some  to  combine  power  and  rapid- 


PEOJECTILES.  189 

ity  of  fire  in  a  more  favorable  degree  than  any  other ; 
hence  this  calibre  predominates  in  the  present  arma- 
ment of  sea-coast  batteries. 

153.  L.arge  cannon.  Special  cannon  of  very  large 
calibre  are  sometimes  mounted  in  parts  of  a  sea-coast 
battery  that  command  narrow  and  important  channels. 
The  intention  in  such  cases  is,  that  the  projectile 
shall  contain  a  large  quantity  of  powder,  a  mine,  in 
fact,  which  shall  destroy,  by  a  single  explosion,  the  ves- 
sel against  which  it  is  directed.  As  the  fire  of  such 
large  pieces  is  slow,  and  the  speed  of  steam  vessels  very 
great,  it  is  evident  that  success  depends  on  the  certainty 
with  which  a  single  shot  strikes  its  object. 

154.  Projectiles.  The  most  effective  projectiles  that 
can  be  brought  to  bear  on  wooden  ships,  are  shells  and 
hot-shot  The  destructive  superiority  of  the  former  was 
well  attested  in  the  Crimean  war,  and  particularly  in 
the  naval  battle  of  Sinope,  where  the  entire  Turkish 
fleet  was  destroyed  by  Russian  shells,  in  about  one 
hour's  time. 

Modern  mechanical  skill  has  succeeded,  to  a  certain 
extent,  however,  in  covering  vessels  of  war  with  plates 
of  wrought  iron,  which  are  proof  against  shells,  and 
solid  projectiles  less  than  8  inches  calibre.  It  is  said 
that  rifle-projectiles  of  less  calibre,  have  power  to  pene- 
trate through  these  coverings  ;  but  they  do  not  produce 
the  shattering  effect  of  round-shot,  which  present  a 
larger  surface,  and,  at  short  ranges,  move  with  a  higher 
velocity.  Should  these  mail-covered  vessels  come  into 
general  use,  it  is  very  probable  that  the  service  of  the 
smaller  sea-coast  guns  will  eventually  be  dispensed  with, 
and  pieces  of  very  large  calibre  be  substituted  for  them. 


190  CANNON. SEA-COAST   CANNON. 

155.  Kinds  of  sea-coast  cannon.  Sea-coast  cannon 
comprise  guns,  columbiads,  howitzers,  and  mortars. 

The  solid-shot  pieces  of  the  sea-coast  service  are, 
the  32-pdr.  and  42-pdr.  guns,  and  the  8-inch,  10-inch, 
and  A  5-inch  columbiads. 

The  form  of  the  sea-coast  guns  in  service,  is  shown  in 
fig.  26.  Those  to  be  made  hereafter,  will  have  no  base- 
ring,  nor  swell  of  muzzle. 

Dimensions,  dec,  of  the  guns.  The  mean  length  of 
bore  is  about  16  calibres. 

The  mean  weight  is  about  200  times  the  solid  shot. 

The  natural  line  of  sight,  being  intercepted  by  the 
reinforce,  an  artificial  one  is  formed  by  affixing  a  sight 
to  the  swell  of  the  muzzle. 

The  charge  of  powder  is  ordinarily  \  the  weight  of  the 
solid  shot. 

The  projectiles  employed  are  solid  shot,  shells,  and 
case-shot. 

The  maximum  angle  of  elevation  when  mounted  in 
barbette  is  11°,  and  in  casemate  it  is  9°. 

156.  Columbiads.  The  columbiads  are  a  species  of 
sea-coast  cannon,  which  combine  certain  qualities  of  the 
gun,  howitzer,  and  mortar;  in  other  words,  they  are 
long,  chambered  pieces,  capable  of  projecting  solid  shot 
and  shells,  with  heavy  charges  of  powder,  at  high  angles 
of  elevation,  and  are,  therefore,  equally  suited  to  the 
defence  of  narrow  channels  and  distant  roadsteads. 

The  columbiad  was  invented  by  the  late  Colonel 
Bomford,  and  used  in  the  war  of  1812  for  firing  solid 
shot.  In  1844  the  model  was  changed,  by  lengthening 
the  bore  and  increasing  the  weight  of  metal,  to  enable 


COLUMBIADS.  191 

it  to  endure  an  increased  charge  of  powder,  or  \  of  the 
weight  of  the  solid  shot. 

Six  years  after  this,  it  was  discovered  that  the  pieces 
thus  altered  did  not  always  possess  the  requisite  length. 
In  1858,  they  were  degraded  to  the  rank  of  shell-guns, 
to  be  fired  with  diminished  charges  of  powder,  and 
their  places  supplied  with  pieces  of  improved  model. 
The  changes  made  in  forming  the  new  model,  consisted 
in  giving  greater  thickness  of  metal  in  the  prolongation 
of  the  axis  of  the  bore,  which  was  done  by  diminishing 
the  length  of  the  bore  itself;  in  substituting  a  hemis- 
pherical bottom  to  the  bore,  and  removing  the  cylindri- 
cal chamber ;  in  removing  the  swell  of  the  muzzle  and 
base-ring ;  and  in  rounding  off  the  corner  of  the  breech. 

From  the  fact  that  all  the  trial  pieces  have  success- 
fully endured  very  severe  tests,  it  is  to  be  inferred  that 
the  defects  of  the  previous  model  arose  from  the  pres- 
ence of  a  cylindrical  chamber,  and  a  deficiency  of  metal 
in  the  prolongation  of  the  bore.* 


Fig.  46. 

*  Six  of  the  trial  pieces  (three  8-in.  and  three  10-in.),  made  at  different  foundries, 
endured  successfully  upward  of  1,000  service-rounds.  Two  10-inch  pieces  (one  cast 
hollow,  and  the  other  cast  solid)  were  fired  2,500  rounds  with  solid  shot  and  14  lbs. 
of  powder,  and  1,632  rounds  with  18  lbs  of  powder  and  solid  shot.  The  only  injury 
sustained  was  the  enlargement  of  the  bore  by  the  cutting  action  of  the  gas  as  it 
passed  over  the  shot.  The  enlargement  of  the  bore  of  the  solid-cast  piece  waa 
much  greater  than  in  the  hollow  one. 


192  CANNON. SEA-COAST    CANNON. 

In  1860,  the  model  proposed  by  Captain  Rodman  was 
adopted  for  all  sea-coast  cannon.  This  model  is  shown 
in  fig.  46 ;  it  does  not  differ,  however,  in  its  essential 
particulars  from  the  model  of  1858. 

Dimensions.  The  following  are  the  principal  dimen- 
sions, &c,  of  the  new  columbiads : 

{8-inch,  about  14  diameters. 
10-inch,      "      12  diameters. 
15-inch,      "      11  diameters. 
(    8-inch     -     -       8,500  lbs. 
Weight,    -     -    -j  10-inch    -     -     15,000  lbs. 
(  15-inch     -     -     50,000  lbs. 

r    8-inch     -     ■     10  lbs. 
Charge,  shot  and  shells,  •<  10-inch     •     -     15  lbs. 

(  15-inch     -     -     40  lbs. 

The  great  disparity  in  the  diameters  of  the  reinforce 
and  muzzle,  renders  it  impracticable  to  affix  an  artificial 
sight  to  the  muzzle ;  a  small  projection  is  therefore  cast 
on  the  upper  side,  between  the  trunnions,  as  a  seat  for 
the  front  sight. 

Vertical  field  of  fire.  The  carriages  permit  the  piece 
to  be  depressed  5°  and  elevated  39°. 

To  facilitate  pointing  in  so  large  a  field  of  fire,  a  slot 
is  cut  in  the  knob  of  the  cascable,  and  a  ratchet  is 
formed  on  the  base  of  the  breech  to  receive  a  "  pawl," 
attached  to  the  head  of  the  elevating  screw. 

If  the  difference  of  elevation  be  greater  than  the 
length  of  a  single  notch  of  the  ratchet,  the  piece  is  rap- 
idly moved  by  a  lever  which  passes  through  an  opening 
in  the  pawl.  If  the  distance  be  less  than  the  length  of 
a  notch,  the  elevating  screw  is  used. 


MORTAKS.  193 

158.  Howitzers.*  A  sea-coast  howitzer  is  a  cham- 
bered piece,  closely  resembling  a  sea-coast  gun  in  exte- 
rior form.  It  is  employed  to  throw  large  hollow  pro- 
jectiles with  reduced  charges  of  powder,  chiefly  in  the 
defence  of  narrow  channels; 

Dimensions,  &c.  The  calibres  are  the  8  and  10  inch. 
The  diameter  of  the  chamber  and  trunnions  of  the  8-inch 
howitzer,  is  the  same  as  the  bore  for  the  32-pdr.  gun,  so 
that  these  two  pieces  may  fit  the  same  kind  of  car- 
riage. The  10-inch  howitzer  bears  the  same  relation  to 
the  42-pdr.  gun. 

Mean  weight,  about  100  times  the  projectile. 

Mean  length  of  bore,  about  10  calibres. 

~,  /»  7       f    8-inch 8  lbs. 

Charge  of  powder,  \  w.nch ^  ^ 

The  howitzers,  like  the  guns,  have  no  naturau  line  of 
sight. 

The  vertical  field  of  fire  is  16°:  11°  above,  and  5°  be- 
low the  horizon. 

Casemate  howitzer.  An  iron  piece  similar  in  form  to 
the  24-pdr.  field  howitzer,  is  employed  to  flank  the  ditches 
of  permanent  works,  principally,  with  canister  shot.  This 
piece  is  sometimes  called  a  garrison  howitzer. 

154.  Mortars.  The  sea-coast  mortars 
differ  from  the  siege  mortars  in  shape 
(jig.  47)  and  weight.  There  are  two  cali- 
bres, the  10  and  13  inch.  Their  weight 
is  about  60  times  the  weight  of  the 
shell,  and  they  are  fired  with  a  charge 
equal  to  TV  the  weight  of  the  shell. 

Fig.  47.  -1  '  ° 

*  These  pieces  are  now  but  little  used.     The  10-inch  has  been  left  out  of  the 
revised  armament  of  the  forts  altogether. 
13 


194 


CANNON. MANUFACTURE    OF. 


Length  of  lore  for  10-inch,  is  2±  calibres. 
"  "  13-inch,  is  2         " 

159.  Carronades.  A  carronade  is  a  cannon,  about  6 
calibres  long  in  the  bore,  and  weighing  about  65  times 
the  weight  of  the  projectile.  It  was  formerly  much 
used  on  ships  of  war  and  fortifications;  and  was  de- 
signed to  throw  a  large  projectile  with  small  velocity, 
for  the  purpose  of  smashing  in,  rather  than  penetrating 
through  the  sides  of  a  ship.  Hence  their  original  name 
of  "  smashers."  A  carronade  has  no  trunnions,  but  is 
supported  on  its  carriage  by  a  stout  bolt,  which  passes 
through  a  loop  cast  on  its  under  side. 


S^Z^itt 


MANUFACTURE   OF  CANNON. 


160.  Where  made.  Cannon  for  the  United  States' 
service  are  made  by  private  founders.  The  material 
and  product  of  the  casting  are  under  the  supervision 
of  an  ordnance  officer,  who  receives  the  pieces  only  after 
they  have  satisfied  all  the  conditions  imposed  by  the 
regulations  of  the  service. 

The  foundries  for  making  cast-iron  cannon  are  at 
Coldspring,  New  York,  South  Boston,  Massachusetts, 
Pittsburgh,  Pennsylvania,  and  Richmond  and  Bellona, 


*  The  new  13-inch  sea-coast  mortar  weighs  1*7.120  lbs., 
and  the  length  of  the  bore  is  about  2.7  diameters.  It  has 
no  preponderance — the  axis  of  the  trunnions  passing 
through  the  centre  of  gravity.  The  form  is  shown  in  fig. 
48 ;  a  represents  the  handle,  and  b  a  ratchet,  cast  upon  the 
breech,  to  receive  the  point  of  a  handspike  for  elevating 
and  depressing  the  piece.  The  weight  of  the  projectile  is 
220  lbs.,  and  the  charge  of  powder  is  20  lbs. 


Fig.  48. 


MOULDING. 


195 


Virginia.     The  principal  foundries  for  bronze  cannon 
are  at  South  Boston  and  Chicopee,  Massachusetts. 

The  manufacture  of  cannon  is  a  valuable  branch  of 
the  work  of  these  foundries,  but  the  orders  of  the  gov- 
ernment are  not  sufficiently  regular  and  extensive  to 
support  them,  and  much  other  work  is  attended  to ;  but 
the  experience  thereby  obtained  in  the  properties  and 
manner  of  treating  metals,  is  useful  in  the  improvement 
of  ordnance. 

The  several  operations  of  manufacturing  cannon  are, 
moulding,  casting,  cooling,  and  finishing. 

161.  Moulding.  Moulding,  in  general  terms,  is  the 
process  by  which  a  cavity  of  the  form  of  the  gun  is  ob- 
tained, by  imbedding  a  wooden  model  in  sand,  and  then 
withdrawing  it. 

The  wooden  model  is  technically  called 
the  u pattern  /"  and  the  sand  is  confined  in 
a  box,  which  is  divided  into  two  or  more 
a  parts,  for  convenience   in  withdrawing  the 
pattern. 

The  pattern  of  the  piece  to  be  cast,  some- 
what enlarged  in  its  different  dimensions,  is 
composed  of  several  pieces  of  hard  wood, 
well  seasoned,  or,  for  greater  durability,  of 
cast  iron.  The  first  piece  of  the  model  com- 
prises the  body  of  the  piece  from  the  base- 
ring  to  the  chase-ring;  the  swell  of  the 
muzzle,  and  the  sprue,  or  dead-head,  are 
formed  of  the  second  piece  (fig.  49) ;  the 
breech,  of  the  third ;  and  the  trunnions,  of 
fourth  and  fifth  pieces.  See  figs.  50  and 
51. 


Fig.  49. 


196  CANNON. MANUFACTURE    OF. 

p^  The  sprue,  usually  called  "the  head"  is 

an  additional  length  given  to  the  piece,  for 

the  purpose  of  receiving  the  scoria  of  the 

melted  metal  as  it  rises  to  the  surface,  and 

furnishing  the  extra  metal  needed  to  feed 

the  shrinkage.     Its  weight  also  increases  the  density  of 

the  lower  portions  of  the  piece. 

The  breech  is  slightly  lengthened   in 

the  direction  of  the  knob  of  the  cascable? 

to  form  a  square  projection  by  which  the 

piece  can  be  held,  when  being  turned  and 
Fig.  6i.         bored 

The  best  material  for  the  mould  is  dry,  hard,  angu- 
lar, and  refractory  sand,  which  must  be  moistened  with 
water  in  which  strong  clay  has  been  stirred,  to  make  it 
sufficiently  adhesive.  When  not  sufficiently  refractory, 
the  sand  is  vitrified  by  the  high  temperature  of  the 
melted  metal,  and  protuberances — not  easily  removed 
— are  formed  on  the  casting.  When  not  sufficiently 
coarse  and  angular,  the  materials  cannot  be  so  united 
as  to  preserve  the  form  of  the  moulds. 

The  mould  is  formed  in  a  case  of  cast- 
iron,  and  termed  the  " box"  or  the  "flask" 
consisting  of  several  pieces,  each  of  which 
has    flanges    perforated   with    holes   for 


Fig.  52.         screw-bolts  and  nuts,  to  unite  the  parts 
firmly.     Fig.  52. 

To  form  the  mould,  the  pattern  for  the  sprue  and 
muzzle,  previously  coated  with  pulverized  charcoal,  or 
coke  moistened  with  clay- water,  to  prevent  adhesion,  is 
placed  vertically  on  the  ground,  muzzle-part  up,  and 
carefully  surrounded  by  the  corresponding  parts  of  the 


MOULDING. 


197 


jacket.     When  properly  adjusted,  the  sand,  prepared 
as  above,   is  rammed  around  it.     The  model  for  the 


Fig.  53. 

body  of  the  piece  is  then  placed  on  the  top  of  this,  and 
the  corresponding  parts  of  the  jacket  correctly  secured 
on,  and  filled  in  succession  with  the  moulding  composi- 
tion. The  patterns  for  the  trunnions  and  rimbases  are 
bolted  to  the  model  of  the  piece,  and  when  the  sand  is 
rammed  firmly  around  these,  the  bolts  are  withdrawn, 
this  part  of  the  mould  completed,  and  the  end-plates 
screwed  on.      Fig.  53. 

After  completing  the  mould  for  the  body  of  the  piece, 
the  model  for  the  cascable  is  properly  adjusted  and  the 
mould  completed. 

Care  is  taken  to  cover  each  portion  of  the  model  with 
the  coke-wash  mentioned  above,  and  to  sprinkle  dry 
sand  upon  the  top  of  the  mould  in  each  piece  of  the 


198  CANNON. MANUFACTURE    OF. 

jacket,  to  prevent  adhesion,  so  that  the  portions  of  the 
mould  may  be  separated. 

In  the  body  of  the  sand,  a  channel  (b)  for  the  intro- 
duction of  the  metal,  is  formed  in  the  same  manner  as 
the  mould  cavity.  It  enters  at  the  bottom  of  the  mould, 
to  prevent  the  bottom  from  being  injured  by  the  falling 
metal,  and  in  an  oblique  direction,  to  give  a  circular 
motion  to  the  metal  as  it  rises  in  the  mould,  and  there- 
by prevent  the  scoria  from  adhering  to  the  sides. 

When  the  mould  is  completed,  the  parts  of  the  flask 
are  carefully  taken  apart,  and  the  pieces  of  the  model 
withdrawn  from  the  mould  contained  in  them.  If  any 
portions  of  the  mould  be  injured  in  withdrawing  the 
model,  they  are  repaired,  and  the  interior  of  the  mould 
is  covered  with  coke-wash ;  after  which  the  several  parts 
are  placed  in  an  oven  to  be  gradually  and  perfectly 
dried.  When  this  is  accomplished,  the  parts  are  car- 
ried to  a  pit,  where  they  are  united  and  secured  in  a 
vertical  position,  with  the  breech  below.  Any  portion 
of  the  sand  broken  off  during  the  movements  and  ad- 
justments, should  be  replaced,  and  the  whole  of  the 
interior  covered  with  coke- wash. 

The  object  of  coke-wash  is  to  prevent  the  sand  from 
adhering  to  the  melted  metal,  which,  when  prepared,  is 
made  to  flow  in  at  the  entrance  of  the  side-channel.  As 
the  metal  rises  in  the  mould,  a  workman  agitates  it  with 
a  long  pine  stick,  to  cause  the  scoria  and  other  impu- 
rities to  rise  to  the  surface,  and  bring  them  toward  the 
centre  of  the  mould  to  prevent  their  entering  the  cavi- 
ties for  the  trunnions. 

162.  Cooling.  After  the  mould  is  placed  properly  in 
the  pit,  it  is  usual  to  surround  the  box  with  sand,  at 


BORING    AND    TURNING.  199 

least  as  high  as  the  trunnions  of  the  gun.  This  is  done 
to  prevent  rapid  cooling.  With  guns  as  heavy  as  24- 
pdrs.,  this  sand  is  not  removed  for  three  days ;  and  as 
the  gun  is  heavier  the  time  is  prolonged,  and  is  from  7 
to  8  days  for  the  10-in.  columbiad.  At  the  proper  time 
this  sand  is  removed,  and  the  gun,  still  imbedded  in  the 
box  and  sand  of  the  mould  proper,  is  hoisted  out,  and 
the  box  taken  off,  and,  when  nearly  cold,  the  gun  cleaned 
of  the  sand.  For  the  method  of  cooling  from  the  in- 
terior,* see  section  102. 

163.  Boring  and  turning.  A  cannon  is  bored  by  giv- 
ing it  a  rotary  motion  around  its  axis,  and  causing  a 
rod  armed  with  a  cutter  to  press  against  the  metal  in 
the  proper  direction. 

The  piece,  supported  in  a  rack,  is  carefully  adjusted, 
with  its  axis  horizontal,  and  made  to  revolve  on  this 
axis,  by  machinery  attached  to  the  square  knob  on  the 
cascable.  After  adjustment,  the  sprue-head  is  first  to 
be  cut  off.  This  is  effected  by  placing  a  cutter  opposite 
the  point  at  which  the  section  is  to  be  made,  and  press- 
ing it  against  the  metal  whilst  the  piece  is  turning. 
The  head  being  cut  off,  and  the  cutter  removed,  the 
boring  is  commenced  by  placing  the  boring-rod,  armed 
with  the  first  cutter,  called  the  piercer,  in  the  prolon- 
gation of  the  axis  of  the  piece,  and  pressing  it  against 
the  metal.  The  piercer  is  used  till  it  penetrates  to  the 
bottom  of  the  chamber,  after  which,  a  second  cutter,  or 
reamer,  is  attached  to  the  boring-rod ;  and  with  this  the 
boring  is  made  complete  to  the  round  part  of  the  cham- 
ber.    The  reamer  is  then  removed,  and  its  place  sup- 

*  All  cast-iron  cannon  for  the  land  service  are  now  required  to  be  cast  hollow, 
and  cooled  from  the  interior,  after  the  plan  of  Captain  Rodman. 


200  CANNON. INSPECTION    OF. 

plied  by  the  chamber-cutter,  which  gives  the  necessary 
form  and  finish  to  that  part  of  the  bore.  In  hollow- 
cast  cannon  the  piercer  is  dispensed  with. 

Whilst  the  boring  is  taking  place,  the  workman  con- 
trives to  finish  the  turning  of  all  the  exterior  of  the 
piece  except  the  portion  between  the  trunnions,  which 
is  afterward  planed  off  in  another  machine. 

These  operations  having  been  completed,  the  piece  is 
placed  in  the  trunnion-machine,  and  the  trunnions  are 
turned  down  to  the  proper  size. 

Care  is  taken  to  make  the  trunnions  of  the  same 
diameter,  and  perfectly  cylindrical.  Their  axes  should 
be  in  the  same  right  line,  perpendicular  to  the  axis  of 
the  piece,  and  intersecting  it. 

Boring  the  vent  Whilst  in  the  trunnion-lathe,  the 
axis  of  the  piece  is  inclined  to  the  horizon  at  the  angle 
the  vent  is  to  make  with  it.  A  drill  is  placed  ver- 
tically over  the  point  where  the  vent  is  to  be  bored, 
and  pressed  against  the  metal  whilst  a  rotary  motion  is 
given  to  it  by  hand  or  machinery. 

The  time  required  to  finish  a  cannon,  ready  for  in- 
spection, depends  upon  its  size,  or  from  three  to  four 
weeks  for  a  24-pdr.  gun,  and  six  weeks  for  an  11 -inch 
gun. 

INSPECTION  OF  CANNON. 

164.  inspecting  instruments.  These  are  used  to  verify 
the  dimensions  of  cannon,  and  to  detect  the  presence 
and  measure  the  size  of  cavities  in  the  metal. 

The  star-gauge  is  an  instrument  for  measuring  the 
diameter  of  the  bore  at  any  point. 

The  cylinder-staff  is  used  to  measure  the  length  of 


INSPECTION.  201 

the  bore.  It  is  supported  by  a  rest  of  a  T  form  at  the 
muzzle,  aud  the  extremity  inserted  in  the  gun  is  armed 
with  a  measuring -point  and  guide-plate. 

The  cylinder  gauge  is  a  cylinder  of  cast  iron,  turned 
to  the  exact  or  true  diameter  of  the  bore.  When  used, 
it  is  attached  to  the  end  of  the  cylinder-staff. 

The  searcher  consists  of  four  flat  springs  turned  up 
at  the  end,  and  attached  to  a  socket  which  is  screwed 
on  to  the  end  of  the  cylinder-staff.  It  is  used  to  feel 
for  cavities  in  the  surface  of  the  bore. 

The  trunnion-gauge  verifies  the  diameters  of  the  trun- 
nions and  rimbases. 

The  trunnion-square  is  used  to  verify  the  position  of 
the  trunnions  with  regard  to  the  bore. 

The  trunnion-rule  measures  the  distance  of  the  trun- 
nions from  the  rear  of  the  base-ring. 

Calipers,  for  measuring  exterior  diameters. 

A  standard-rule,  for  verifying  other  instruments. 

The  vent-gauges  are  two  pointed  pieces  of  steel  wire, 
0.005  inch  greater  and  less  than  the  true  diameter  of 
the  vent,  to  verify  its  size. 

The  .vent-searcher,  is  a  hooked  wire,  used  to  detect 
cavities  in  the  vent. 

A  rammer-head,  shaped  to  the  .form  of  the  bottom 
of  the  bore,  and  furnished  with  a  staff,  is  used  to  ascer- 
tain the  interior  position  of  the  vent. 

A  wooden  rule  to  measure  exterior  lengths. 

A  mirror;  a  wax  taper;  bees-wax. 

Hammer,  sponge,  and  priming-wire. 

Figure  and  letter  stamps,  to  affix  the  required  marks. 

165.  inspection.  The  objects  of  inspecting  cannon 
are  to  verify  their  dimensions,  particularly  those  which 


202  CANNON. INSPECTION    OF. 

affect  the  accuracy  of  fire,  and  the  relation  of  the  piece 
to  its  carriage,  and  to  detect  any  defects  of  metal  and 
workmanship,  that  would  be  likely  to  impair  their 
strength  and  endurance. 

Cannon  presented  for  inspection  and  proof,  are  placed 
on  skids,  for  the  convenience  of  turning  and  moving 
them  easily.  They  are  first  examined  carefully  on  the 
exterior,  to  ascertain  whether  there  are  any  flaws  or 
cracks  in  the  metal,  whether  they  are  finished  as  pre- 
scribed, and  to  judge,  as  well  as  practicable,  of  the 
quality  of  the  metal.  They  must  not  be  covered  with 
paint,  lacquer,  or  any  other  composition.  If  it  be  ascer- 
tained that  an  attempt  has  been  made  to  conceal  flaws 
or  cavities,  by  plugging  them,  the  gun  is  rejected  with- 
out further  examination. 

After  this  preliminary  examination,  the  inspector  pro- 
ceeds to  verify  the  dimensions  of  the  piece. 

The  interior  of  the  bore  is  first  examined  by  reflecting 
the  sun's  rays  into  it  from  a  mirror ;  or  by  a  lighted 
wax-taper  placed  at  the  end  of  a  long  rod,  and  inserted 
into  the  bore.  The  searcher  is  then  introduced,  and 
pushed  slowly  to  the  bottom  of  the  bore,  and  with- 
drawn, turning  it  at  the  same  time  ;  if  one  of  the  points 
hangs,  the  position  of  the  hole  is  marked  on  the  outside 
of  the  gun,  by  noticing  its  distance  from  the  muzzle, 
and  its  position  in  the  bore ;  the  size  and  figure  of  the 
cavity,  are  found  by  taking  an  impression  of  it  in  wax, 
placed  on  the  end  of  a  hook. 

The  cylinder  gauge,  screwed  on  the  staff,  is  then 
pushed  gently  to  the  bottom  of  the  cylindrical  part  of 
the  bore,  and  withdrawn ;  it  must  go  to  the  bottom,  or 
the  bore  is  too  small. 


INSPECTION.  203 

The  bore  is  then  measured  with  the  star-gauge.  The 
measurements  should  be  made  at  intervals  of  \  inch  in 
the  part  of  the  bore  occupied  by  the  shot ;  at  intervals 
of  one  inch  in  rear  of  the  trunnions,  and  of  about  one 
calibre  from  the  trunnions  to  the  muzzle. 

The  position  of  the  trunnions,  with  regard  to  the  axis 
of  the  bore,  and  to  each  other,  is  next  ascertained. 

To  verify  the  position  of  the  axis  of  the  trunnions,  set 
the  trunnion-square  on  the  trunnions,  and  see  that  the 
lower  edges  of  its  branches  touch  them  throughout  their 
whole  length ;  push  the  slide  down  till  it  touches  the 
surface  of  the  piece,  and  secure  it  in  that  position  by 
the  thumb-screw;  turn  the  piece  over,  and  apply  the 
trunnion-square  to  the  opposite  side,  and  if,  when  the 
point  of  the  slide  touches  the  surface  of  the  piece,  the 
lower  edges  of  the  branches  rest  on  the  trunnions,  the 
axis  of  the  trunnions  is  in  the  same  plane  with  the  axis 
of  the  bore ;  if  they  do  not  touch  the  trunnions,  their 
axis  is  above  the  axis  of  the  bore  by  half  the  space  be- 
tween ;  and  if  the  edges  touch  the  trunnions,  and  the 
point  of  the  slide  does  not  touch  the  surface  of  the 
piece,  their  axis  is  below  the  axis  of  the  bore.  If  the 
alignment  of  the  trunnions  be  accurate,  the  edges  of  the 
trunnion-square  will  fit  on  them,  when  applied  to  dif- 
ferent parts  of  their  surface ;  their  diameter  and  cylin- 
drical form,  and  the  diameter  of  the  rimbases,  are  veri- 
fied with  the  trunnion-gauge. 

To  ascertain  the  length  of  the  bore,  screw  the  guide- 
plate  and  measuringpoint  on  the  cylinder-staff,  and 
push  them  to  the  bottom  of  the  bore ;  place  a  half 
tompion  in  the  muzzle,  and  rest  the  staff  in  its  groove ; 


204  CANNON. INSPECTION    OF. 

apply  a  straight-edge  to  the  face  of  the  muzzle,  and  read 
the  length  of  the  bore  on  the  staff. 

The  exterior  lengths  are  measured  by  the  rule,  or  by 
a  profile,  the  accuracy  of  which  is  first  verified. 

The  exterior  diameters  are  measured  with  the  cali- 
pers and  graduated  rule. 

The  position  of  the  interior  orifice  of  the  vent  is  found 
from  the  mark  on  the  rammer-head  by  the  vent-gauge, 
inserted  in  the  vent  while  the  rammer-head  is  held 
against  the  bottom  of  the  bore;  two  impressions  are 
taken.  The  position  of  the  exterior  orifice  of  the  vent 
is  also  verified.  The  vent  is  examined  with  the  gauges, 
and  with  the  vent-searcher,  to  ascertain  if  there  be  any 
cavities  in  it. 

In  mortars,  the  dimensions  of  the  conical  chambers 
and  the  form  of  the  breech,  may  be  verified  with  pat- 
terns made  of  plate-iron.  After  the  powder-proof  the 
bore  is  washed  and  wiped  clean,  and  the  bore  and 
vent  again  examined,  and  the  diameter  of  the  bore 
remeasured. 

The  results  of  each  of  the  measurements  and  exami- 
nations are  noted  on  the  inspection  report  against  the 
number  of  the  gun. 

166.  Bronze  cannon.  That  the  finished  bore  of  a 
bronze  piece  may  not  be  injured  by  the  proof-charge,  it 
is  bored  out  under  size,  from  .04  to  .05  inch,  and,  after 
proof,  reamed  out  to  the  true  size.  When  the  powder- 
proof  is  finished,  the  bore  should  be  cleaned  and  exam- 
ined ;  the  vent  should  be  stopped  up  with  a  greased 
wooden  plug,  the  muzzle  raised,  and  the  gun  filled  with 
water,  to  which  pressure  should  be  applied  to  force  it  into 
any  cavities  that  exist ;  or  the  water  should  be  allowed 


POWDER-PKOOF.  205 

to  remain  in  the  bore  twenty-four  hours.  The  bore  must* 
then  be  sponged  dry  and  clean,  and  viewed  with  a  mir- 
ror or  candle,  to  discover  if  any  water  oozes  from  cracks 
or  cavities,  and  also,  if  any  enlargement  has  taken  place. 
The  quantity  that  runs  out  of  a  crack  or  honey-comb 
will  indicate  the  extent  of  the  defect ;  and  if  it  exceed 
a  few  drops,  the  piece  should  be  rejected,  although  the 
measured  depth  of  the  cavity  may  not  exceed  the  allow- 
ance. 

After  the  bore  has  been  reamed  out  to  its  proper 
size,  its  dimensions  are  again  verified,  and  an  examina- 
tion of  the  bore  and  vent  is  made,  to  detect  any  defects 
which  may  have  been  caused  or  developed  by  the  proof. 

Whitish  spots  show  a  separation  of  the  tin  from  the 
copper,  and,  if  extensive,  should  condemn  the  piece. 

A  great  variation  from  the  t/rue  weight,  which  the 
dimensions  do  not  account  for,  shows  a  defect  in  the 
alloy. 

Bronze  cannon  should  be  rejected  for  the  following 
sized  cavities  or  honey-combs : 

Exterior.  Any  hole  or  cavity  0.25  in.  deep  in  front 
of  the  trunnions,  and  0.2  in.  deep  at  or  behind  the 
trunnions. 

Interior.  From  the  muzzle  to  the  reinforce,  any 
cavity  0.15  deep.  Any  cavity  from  the  reinforce  to  the 
bottom  of  the  bore. 

In  all  other  respects,  the  inspection  of  cast-iron  and 
bronze  cannon  are  alike. 

PROOF  OF  CANNON. 
167.  Powder-proof.  Gunpowder  for  proving  ordnance 


206  CANNON. PROOF    OF. 

should  be  of  the  best  quality,  ranging  not  less  than  250 
yds.  by  the  eprouvette.  The  cartridge-hags  are  made  of 
woollen  stuff  or  paper,  the  full  diameter  of  the  bore  or 
chamber.  They  are  filled  by  weight,  and  if  not  filled  at 
the  place  where  the  guns  are  proved,  each  bag  should 
be  enveloped  in  a  paper  cylinder  and  cap,  marked  with 
the  weight  of  powder  and  its  proof-range. 

The  shot  must  be  smooth,  free  from  seams  and  other 
inequalities  that  might  injure  the  bore  of  the  piece,  and 
they  must  be  of  the  true  diameter  given  in  the  tables. 

168.  iron  cannon.  Guns  and  howitzers  are  laid  with 
the  muzzle  resting  on  a  block  of  wood,  and  the  breech 
on  the  ground  or  on  a  plank,  giving  the  bore  a  small 
elevation. 

Mortars  are  mounted  on  strong  wooden  frames  or 
beds,  at  an  elevation  of  45°,  supported  by  the  trunnions. 

Guns,  dec.  Gruns,  howitzers  and  columbiads,  are  fired 
three  times,  with  a  solid  shot  and  a  charge  of  powder 
somewhat  greater  than  the  service  charge. 

In  proving  new  guns,  compound  shot,  or  a  cylinder 
with  hemispherical  ends,  of  the  true  diameter  of  the 
shot,  and  equal  in  weight  to  the  two  shot,  shall  be  used 
instead  of  them. 

Should  any  of  the  guns  proved  at  one  time,  fail  to 
sustain  the  above  proof,  the  remainder  shall  be  rejected, 
if  made  of  the  same  metal  and  treated  in  the  same 
manner. 

Mortars  are  proved  in  the  same  manner  as  the  above, 
with  the  exception  that  shells  filled  with  sand  are  used 
in  place  of  shot. 

169.  Bronze  eannon  are  fired  three  times  with  solid 
shot  and  a  charge  of  powder  one-third  the  weight  of  the 


INJUEIES.  207 

shot.  If  the  piece  has  been  in  service,  or  if  it  be  new, 
and  its  bore  be  of  the  true  size,  the  shot  should  be 
wrapped  in  cloth  or  strong  paper,  to  save  the  bore  as 
much  as  possible  from  injury. 

170.  inspection  marks.*  All  cannon  are  required  to 
be  weighed,  and  to  be  marked  as  follows,  viz. :  the  num- 
ber of  the  gun,  the  initials  of  the  inspectors  name,  on 
the  face  of  the  muzzle — the  numbers,  in  a  separate  series, 
for  each  kind  and  calibre  at  each  foundry ;  the  initial 
letters  of  the  name  of  the  founder  and  the  foundry,  on 
the  end  of  the  right  trunnion;  the  year  of  fabrication, 
on  the  end  of  the  left  trunnion ;  the  foundry  number, 
on  the  end  of  the  right  rimbase,  above  the  trunnion; 
the  weight  of  the  piece  in  pounds,  on  the  base  of  the 
breech ;  the  letters  U.  S.,  on  the  upper  surface  of  the 
piece,  near  the  end  of  the  reinforce. 

The  natural  line  of  sight,  when  the  axis  of  the  trun- 
nions is  horizontal,  should  be  marked  on  the  base-ring 
and  on  the  swell  of  the  muzzle,  whilst  the  piece  is  in 
the  trunnion-lathe. 

Cannon  rejected  on  inspection,  are  marked  XC,  on  the 
face  of  the  muzzle ;  if  condemned  for  erroneous  dimen- 
sions which  cannot  be  remedied,  add  XD ;  if  by  powder- 
proof,  XP ;  if  by  water-proof,  XW. 


INJURIES  CAUSED  BY  SERVICE. 

171.  External.  The  only  external  injury  of  import- 
ance, is  the  bending  of  the  trunnions  of  bronze  cannon 
by  long  firing. 

*  In  cannon  modelled  in  1861,  all  the  marks  are  placed  on  the  face  of  the  muzzle. 


208  CANNON. INJUKIES. 

172.  internal.  Internal  injuries  arise  from  the  sepa- 
rate actions  of  the  powder  and  the  projectile.  They  in- 
crease in  extent  with  the  calibre,  whatever  may  be  the 
nature  of  the  piece,  but  are  modified  by  the  material  of 
which  it  is  made. 

Injuries  from  the  powder.  The  injuries  from  the  pow- 
der generally  occur  in  rear  of  the  projectile.     They  are, 

1st.  The  enlargement  of  that  portion  of  the  bore 
which  contains  the  powder,  arising  from  the  compression 
of  the  metal.  This  injury  is  more  marked  when  a  sabot 
or  wad  is  placed  between  the  powder  and  projectile, 
and  is  greatest  in  a  vertical  direction. 

2d.  Cavities,  produced  by  the  melting  away  of  a 
portion  of  the  metal  by  the  heat  of  combustion  of  the 
charge. 

3d.  Cracks,  arising  from  the  tearing  asunder  of  the 
particles  of  the  metal  at  the  surface  of  the  bore.  At 
first  a  crack  of  this  kind  is  scarcely  perceptible,  but  it 
is  increased  by  continued  firing  until  it  extends  com- 
pletely through  the  side  of  the  piece.  It  generally  com- 
mences at  the  junction  of  the  chamber  with  the  bore, 
as  this  portion  is  less  supported  than  others. 

4th.  Furrows,  produced  by  the  erosive  action  of  the 
inflamed  gases.  This  injury  is  most  apparent  where  the 
current  of  the  gas  is  most  rapid,  or  at  the  inner  orifice 
of  the  vent,  and  on  the  surface  of  the  bore,  immediately 
over  the  seat  of  the  projectile. 

The  wear  of  the  vents  of  bronze  cannon  is  obviated 
by  inserting  a  copper  vent-piece  (par.  84).  The  effect  of 
continuous  firing  on  the  vents  of  iron  cannon  is  to  pro- 
duce a  uniform  enlargement  of  the  inner  orifice,  and  to 
seriously  weaken  the  piece.     The  appearance  of  a  vent 


INJURIES.  209 

thus  enlarged,  is  irregular  and  angular,  with  its  greatest 
diameter  in  the  direction  of  the  axis  of  the  bore. 

To  obviate  the  serious  consequences  that  result  from 
this  injury,  Captain  Dahlgren  has  placed  in  his  naval 
guns  two  vents,  each  a  short  distance  from,  and  on  op- 
posite sides  of,  the  vertical  plane  passing  through  the 
axis  of  the  piece.  One  of  them  is  filled  with  melted 
zinc;  the  other  is  used  until  it  becomes  so  much  en- 
larged as  to  endanger  the  safety  of  the  piece ;  it  is  then 
filled  with  zinc,  and  the  first  one  is  opened. 

Injuries  from  the  projectile.  The  injuries  arising 
from  the  action  of  the  projectile  occur  around  the  pro- 
jectile, and  in  front  of  it.     They  are, 

1st.  The  lodgement.  This  is  an  indentation  in  the 
lower  side  of  the  bore,  produced  by  the  pressure  upon 
the  ball  by  the  escape  of  the  gas  through  the  windage, 
before  the  ball  has  moved  from  its  seat.  The  elasticity 
of  the  metal,  and  the  burr,  or  crowding  up,  of  the  metal 
in  front  of  the  projectile,  cause  it  to  rebound,  and  being 
carried  forward  by  the  force  of  the  charge,  to  strike 
against  the  upper  side  of  the  bore,  a  short  distance  in 
front  of  the  trunnions.  From  this  it  is  reflected  against 
the  bottom,  and  re-reflected  against  the  top  of  the  bore, 
and  so  on  until  it  leaves  the  piece. 

The  first  indentation  is  called  the  lodgement ;  the 
others,  enlargements.  In  pieces  of  ordinary  length, 
there  are  generally  three  enlargements,  when  this  injury 
first  makes  its  appearance,  but  their  number  is  increased 
as  the  lodgement  is  deepened  and  the  angle  of  inci- 
dence increased.  Brass  pieces  are  considered  unservice- 
able when  the  depth  of  the  lodgement  is  .18  in.,  and 
the  depth  of  an  enlargement  is  .16  in. 

14 


210  CANNON. INJURIES. 

The  effect  of  this  bounding  motion,  is  to  alternately 
raise  and  depress  the  piece  in  its  trunnion-beds,  and  to 
diminish  the  accuracy  of  fire,  until  finally,  the  piece 
becomes  unfit  for  service. 

It  is  principally  from  this  injury  that  bronze  guns 
become  unserviceable.  Mortars  and  howitzers  are  not 
much  affected  by  it. 

The  principal  means  used  to  obviate  this  injury,  are 
to  wrap  the  projectile  with  cloth  or  paper  (as  the  cyl- 
inder cap  of  the  cartridge  used  with  field-guns),  and  .to 
shift  the  seat  of  the  projectile.  The  latter  may  be  done 
by  a  wad,  or  lengthened  sabot,  or  by  reducing  the  diam- 
eter and  increasing  the  length  of  the  cartridge.  The 
last  of  these  methods  is  considered  the  most  practical 
as  well  as  the  most  effective ;  and  it  has  the  additional 
advantage  of  diminishing  the  strain  on  the  bore,  by 
increasing  the  space  in  which  the  charge  expands  before 
the  ball  is  moved. 

The  French  bronze  siege-guns,  which  formerly  were 
rendered  unserviceable  in  600  service-rounds,  now  en- 
dure, by  this  method,  2,500  service-rounds. 

2d.  Scratches,  or  furrows  made  upon  the  surface  of 
the  bore  by  rough  projectiles,  or  by  case-shot.  This  is 
not  a  serious  injury. 

3d.  Cuts,  made  by  the  fragments  of  projectiles  which 
break  in  the  bore. 

4th.  Enlargement  of  the  bore,  arising  from  the  com- 
pression of  the  metal  by  the  powder. 

5th.  Enlargement  of  the  muzzle,  arising  from  the 
forcing  outward  of  the  metal  by  the  striking  of  the 
projectile  against  the  side  of  the  bore,  as  it  leaves  the 


INJURIES.  211 

piece.     By  this  action,  the  shape  of  the  muzzle  is  elon- 
gated in  a  vertical  direction. 

6th.  Cracks  on  the  exterior.  These  are  formed  by 
the  compression  of  the  metal  within,  generally  at  the 
chase,  where  the  metal  is  thinnest.  This  portion  of 
a  bronze  gun  is  the  first  to  give  way  by  long  firing, 
whereas,  cast-iron  cannon  are  burst  in  rear  of  the  trun- 
nion, and  the  fracture  passes  through  the  vent,  if  it  be 
much  enlarged. 

Cast-iron  cannon.  The  principal  injuries  to  which 
cast-iron  cannon  are  liable  are,  the  enlargement  of  the 
vent  by  service,  and  the  change  in  the  size  and  form  of 
the  bore,  and  the  enlargement  of  cavities,  by  rust. 

It  has  been  seen  that  the  strength  of  cast-iron  cannon 
is  diminished  by  repeated  firing ;  there  is  a  limit,  there- 
fore, beyond  which  they  should  not  be  used.  This 
limit  has  not  been  fixed  by  regulation  for  American 
cannon;  but  it  is  inferred  from  the  test  standard  (sec. 
Ill),  that  no  cast-iron  piece  will  be  called  upon  to  en- 
dure more  than  1,000  service-rounds,  except  in  case  of 
emergency. 

The  number  of  times  which  an  iron  piece  has  been 
fired  may  be  approximately  determined  by  the  size  of 
the  bore  and  the  vent.  The  first  is  taken  by  the  "  star- 
gauge,"  and  the  second,  by  taking  an  impression  in  wax. 


212  ARTILLEEY    CARRIAGES. 


CHAPTER  IV. 
ARTILLERY   CARRIAGES. 

173.  Classification.  Artillery  carriages  may  be  di- 
vided into  two  classes,  viz.,  those  employed  for  the 
immediate  service  and  transportation  of  cannon,  as  gun- 
carriages  and  mortar-beds,  and  those -employed  for  the 
transportation  of  ammunition,  implements,  and  materials 
for  repairs,  as  caissons*,  mortar-wagons,  forges,  and  bat- 
tery-wagons. 

The  points  to  be  considered  in  the  construction  of  all 
carriages  are  those  which  relate  to  the  draught,  those 
which  refer  to  the  load  to  be  transported,  and  (in  the 
particular  case  of  artillery  carriages)  those  which  relate 
to  the  service  of  the  piece. 

Under  the  .first  head  will  be  considered  the  liorse  as 
a  motive  power,  the  harness  and  its  mode  of  attachment 
to  the  carriage,  and  the  wheel,  in  its  relation  to  fric- 
tion, &c. 

The  horse  transports  his  load  in  two  distinct  ways : 
1st,  as  sl pack-horse  ;  2d,  as  a  draught-horse. 

IT 4.  Pack-horse.  The  load,  gait,  journey,  forage, 
intervals  of  rest,  &c,  of  a  work-horse  should  be  so  pro- 
portioned that  he  will  be  no  more  fatigued  one  day  than 
another. 

It  has  been  determined  by  experience,  that  a  pack- 
horse,  travelling  at  a  walk,  over  a  good  road,  can  carry 


DRAUGHT-HORSE.  213 

from  220  to   300  lbs.,  30  miles  in   10  hours ;  or  if  lie 
moves  at  a  trot,  175  lbs.  over  the  same  distance. 

The  daily  work  of  a  pack-horse  is  equal  to  that  of 
five  men,  under  the  same  circumstances.  If  the  road  be 
hilly  the  advantage  will  be  in  favor  of  the  men. 

The  above  data  suppose  that  the  animal  is  regularly 
fed  on  the  service-ration.  If  he  be  fed  on  grass  alone, 
an  allowance  must  be  made  for  its  quality  and  abun- 
dance. 

In  some  respects  the  mule  is  a  superior  pack-animal 
to  the  horse.  His  peculiar  build  gives  him,  in  propor- 
tion to  his  weight,  a  greater  j)ower  to  transport  a  load 
on  his  back ;  besides  this,  the  mule  eats  less  than  the 
horse,  and  is  more  sure-footed. 

175.  »raugiit-iior§e.  The  force  exerted  by  a  draught- 
horse  may  be  divided  into  two  parts,  viz.,  that  which 
overcomes  the  inertia  and  friction  of  the  carriage  and 
sets  it  in  motion,  and  that  which  is  necessary  to  over- 
come the  resistances  which  recur  along  its  path.  The 
first,  being  of  momentary  duration,  may  approximate 
the  utmost  strength  of  the  animal ;  its  intensity  should 
be  known  in  order  to  give  the  necessary  strength  to  the 
harness. 

If  Q  represent  the  mean  force  (in  lbs.)  exerted  by  a 
horse,  in  a  unit  of  time,  in  drawing  a  load  over  a  road, 
the  length  of  which  is  Z,  Ql  represents  the  quantity  of 
work  performed.  The  direction  of  the  force  is  taken 
parallel  to  the  plane  along  which  the  load  moves.  If  it 
make  an  angle,  a,  with  this  plane,  the  work  will  be  de- 
composed into  two  components,  Ql  cos.  a,  which  is  par- 
allel to  the  plane,  and  Ql  sin.  #,  which  is  perpendicular 
to  it :  the  latter  transfers  a  portion  of  the  load  from 


214 


AETILLERY    CARRIAGES. 


the  ground  to  the  horse's  shoulders,  thereby  increasing 
his  friction,  and  to  a  certain  extent  the  power  of  trac- 
tion. 

Momentary  effort.  Careful  experiments  have  been 
made  in  France  to  determine  the  proportion  of  those  two 
components  most  favorable  to  the  exercise  of  the  horse's 
power.  It  was  found  that  the  most  suitable  angle  for 
the  traces  of  an  unloaded  horse,  with  the  ground,  was 
from  10°  to  12° ;  and  for  a  horse  that  carried  his  driver, 
from  6°  to  1° ;  or,  in  other  words,  a  draught-horse  should 
carry  \  of  his  load  on  his  back. 

Continuous  effort.  The  relation  between  the  weight 
of  a  loaded  carriage  and  the  force  to  be  expended  by  the 
horse  to  keep  it  in  motion,  depends  upon  so  many  cir- 
cumstances that  it  is  impossible  to  give  a  general  ex- 
pression for  its  determination.  It  can  only  be  deter- 
mined by  direct  experiment  in  each  particular  case. 


NATURE    OF 
CARRIAGE. 

NATURE    OP    ROAD. 

GAIT. 

VALUE  OF 

m 

Spring  carriages. 

Pavement  in  good  con- 
dition. 

Slow  walk. 
Fast  walk. 
Slow  trot. 
Fast  trot. 

iV 

JL 

36 

1 
24 

1  a 

All  gaits. 

1 
23 

Slightly  sandy. 
Very  sandy. 

All  gaits. 

1 

2  2 

V 

1  0 

Field  artillery  car- 
riages. 

Turf. 

Newly  ploughed  up  and 
dug  over. 

Walk. 

u 

JL 

2  2 

rV 

The  foregoing  table  embraces  the  results  of  some  ex- 


HARNESS.  215 

periments  on  this  point,  in  which  m  is  the  ratio  of  the 
weight  of  the  loaded  carriage  and  the  force  of  traction ; 
whence  it  is  seen  that  a  carriage  moving  over  a  rough 
or  paved  road,  meets  with  a  resistance  which  increases 
rapidly  with  its  velocity ;  but  over  a  smooth  or  sandy 
road,  the  resistance  to  draught  is  independent  of  the 
velocity. 

The  load  allotted  to  an  artillery  horse  is  less  than 
that  usually  drawn  by  a  horse  of  commerce,  for  the 
reason  that  allowance  must  be  made  for  bad  roads,  bad 
forage,  rapid  movements,  and  forced  marches.  They  are 
as  follows : 

Light  artillery  horse,     700  lbs.,  including  carriage. 
Heavy  field  artillery,     850    "  "  u 

Siege  artillery,  1,000    "  "  " 

The  above  is  based  on  the  rapidity  of  movement  re- 
quired in  the  different  services. 

An  ordinary  draught-horse  can  draw  1,600  lbs.  23 
miles  in  a  day. 

Usually,  a  horse  can  draw  7  times  as  much  as  he  can 
carry ;  hence,  all  material  of  war  should  be  transported 
on  carriages,  if  practicable. 


HARNESS. 

176.  Requirements  The  best  method  of  attaching 
horses  to  a  carriage  is  that  which  enables  each  one  to 
perform  a  given  amount  of  work  with  the  least  fatigue ; 
or,  in  other  words,  no  horse  should  be  restrained  by  the 


216  ARTILLERY    CARRIAGES. 

efforts  of  another,  and  the  direction  of  the  traces  should 
be  most  favorable  for  draught. 

Besides  these  conditions,  artillery-harness  should  be 
so  constructed  that  it  can  be  put  on  and  taken  off 
promptly,  by  night  as  well  as  by  day,  in  all  states  of 
the  weather,  and  in  cases  of  danger,  when  the  drivers 
would  be  liable  to  lose  their  presence  of  mind.  The 
fall  of  one  horse  should  not  interfere  with  another ;  and 
a  dead  or  wounded  horse  should  be  easily  replaced, 
whatever  may  be  his  position  in  the  team.  The  ab- 
sence of  some  of  the  horses,  the  unhitching  or  cutting 
of  some  of  the  traces  should  not  arrest  the  movement 
of  the  carriage.  Finally,  the  drivers,  who  are  mounted 
for  the  better  command  of  their  horses,  should  not  be 
incommoded  by  the  pole  of  the  carriage. 

177.  ]*iode§  of  attachment.  There  are  three  general 
modes  of  attaching  horses  to  artillery  carriages,  and 
upon  the  employment  of  any  one  of  which  depends  the 
construction  of  the  harness. 

In  the  first  method  the  wheel-horse  is  placed  between 
two  shafts,  by  which  he  guides  and  regulates  the  motion 
of  the  carriage. 

The  horses  may  be  arranged  in  single  or  double  file. 
The  former  arrangement  was  much  in  vogue  in  artillery 
before  the  days  of  Gribeauval,  but  at  present  is  only 
employed  in  the  mountain  service. 

This  method  has  the  merit  of  being  well  suited  for 
drawing  heavy  loads  over  smooth  roads,  but  is  not 
adapted  to  rapid  movements  over  ordinary  roads,  as 
much  of  the  tractile  force  is  lost  by  the  continued 
change  in  the  line  of  traction  incident  to  long  columns. 
The  force  thus  lost  is  expended  in  a  great  measure  on 


PRESENT   METHOD.  217 

the  shaft-horse,  which,  by  constant  fatigue,  is  soon  ren- 
dered unserviceable. 

In  the  English  light  artillery  the  horses  are  arranged 
in  double  file,  'the  off  wheel-horse  being  placed  in  shafts. 

178.  Gribeauvai'i  method.  In  the  second  method,  the 
horses  are  arranged  in  double  file — a  wheel-horse  being 
placed  on  each  side  of  the  pole,  which  is  attached  to 
the  front  axle-tree. 

The  pole  is  supported  and  kept  steady  by  the  pressure 
of  the  body  of  the  carriage  on  the  sweep-bar,  which  pro- 
jects  in  rear  of  the  front  axle-tree.  The  leading  horses 
are  attached  to  the  swing-tree,  which  is  fastened  to  the 
pole,  and  the  wheel-horses  are  attached  to  a  movable 
splinter-bar,  the  centre  of  which  is  in  the  axis  of  the 
pole.  The  object  of  making  a  splinter-bar  movable  is 
to  equalize  the  draught  between  two  horses,  one  of 
which  works  more  freely  than  the  other. 

This  system  of  attachment  is  used  in  most  carriages 
of  commerce,  and  so  far  as  the  draught  alone  is  con- 
cerned, is  superior  to  all  others.  It  is  also  used  in  all 
siege-carriages,  and  baggage- wagons  of  the  military 
service,  except  that  in  the  former  the  splinter-bar  is 
fixed. 

179.  Pre§ent  method.  In  field-carriages  of  late  pat- 
tern the  siveep-bar  is  omitted,  to  facilitate  attaching  and 
detaching  the  rear  carnage  in  time  of  action ;  and  the 
pole  is  supported  by  two  yokes  attached  to  the  collars 
of  the  horses.  The  wheel-horses  are  attached  to  a  fixed 
splinter-bar,  which  is  strong  and  simple  in  its  construc- 
tion ;  and  the  traces  of  the  leading  horses  are  attached 
directly  to  those  in  the  rear,  giving  a  continuous  line  of 
traction,  communicating  directly  with  the  carriage.   This 


218 


ARTILLERY    CARRIAGES. 


method  of  attaching  artillery-horses  in  line  is  extremely 
simple,  and  at  the  same  time  it  fulfils  nearly  all  the 
conditions  requisite  for  artillery  harness.  Its  principal 
defect,  however,  is  that,  from  the  want  of  a  sweep-bar 
the  weight  of  the  carriage-pole  is  borne  on  the  necks  of 
the  wheel-horses,  which  is  a  serious  inconvenience  in 
long  marches. 

How  composed.  Artillery  harness  is  composed  of  the 
head-gear,  to  guide  and  hold  the  horse ;  the  saddle,  for 
the  transportation  of  the  driver  and  his  valise;  the 
draught-harness,  which  enables  the  horse  to  move  the 
carriage  forward ;  and  the  breeching,  which  enables  him 
to  hold  it  back,  stop  it,  or  move  it  to  the  rear. 

Head-gear.  The  head-gear  is  composed  of  the  bridle, 
by  which  the  horse  is  guided,  and  the  halter,  by  which 
he  is  held  when  detached  from  the  carriage. 


Fig.  54. 

Saddle.  A  riding-saddle  (2,  fig.  54)  is  placed  on 
each  near  horse,  for  the  driver,  and  a  valise-saddle  on 
each  off  horse. 

Draught-harness.  This  is  composed  of  a  collar  (1), 
which  serves  as  a  cushion  for  the  hames  to  rest  upon, 
without  injuring  the  horse's  shoulders.  The  hames  are 
two  curved  pieces  of  iron,  which  embrace  the  collar,  and 


PEESEEVATION.  219 

are  fastened  together  at  the  top  and  bottom.  To  each 
hame  is  attached  a  stout  leather  tug  (5),  which  termi- 
nates in  an  iron  ring,  to  which  the  trace  is  attached. 
The  traces  are  stout  leather  straps,  terminated  at  each 
end  with  chains,  and  are  used  in  pulling  the  carriage. 
The  chain  at  the  rear  extremity  is  used  to  shorten  or 
lengthen  the  trace  at  will.  The  forward  chain  plays 
back  and  forth  in  the  ring  of  the  tug,  which  makes  the 
wheel-horse  independent  of  the  leading  horses.  The 
pole-yoke  (8)  is  supported  by  a  chain  attached  to  the 
hame-clasp,  and  a  ring  which  slides  along  the  yoke. 
The  branches  of  the  yoke  are  jointed  to  a  collar  near 
the  extremity  of  the  pole,  in  such  manner  that  they  can 
only  play  in  a  plane  passing  through  the  axis  of  the 
pole.  This  arrangement  enables  the  horse  to  keep  the 
pole  steady  without  constraining  his  motion. 

Breeching.  The  breeching  is  composed  of  the  breech- 
strap  (6),  breast-strap,  and  hip-strap  (10).  The  breech- 
strap  and  breast-strap  united,  completely  encircle  the 
horse.  They  are  attached  to  the  pole-strap  (7)  by  an 
iron  loop.  The  hip-strap  sustains  the  breeching  as  it 
passes  around  the  horse's  flanks. 

The  harness  of  the  leading  horses  has  no  breeching ; 
in  all  other  respects,  it  is  similar  to  that  of  the  wheel- 
horses. 

180.  Preservation,  &c.  A  storehouse  for  harness 
should  be  well  ventilated — not  too  dry,  but  free  from 
dampness.  The  different  articles  should  be  arranged  in 
bundles,  according  to  kind  and  class,  without  touching 
the  wall  or  each  other.  Harness  should  be  examined 
four  times  a  year,  at  least.  The  leather  parts  are 
brushed  and  greased  with  neatsfoot  oil  as  often  as  con- 


220  ARTILLERY    CARRIAGES. 

dition  requires ;  if  they  have  a  reddish  hue,  add  a  little 
lampblack  to  the  oil.  The  hair  side  of  the  leather 
should  be  wet  with  a  sponge  dipped  in  warm  water, 
and  the  oil  applied  before  the  surface  is  dry.  The  iron 
parts  which  are  not  japanned  should  be  covered  with 
tallow. 

WHEEL. 

181.  Nomenclature.  All  artillery  carriage  wheels 
are  similarly  constructed;  they  differ,  however,  in  the 
size  and  strength  of  certain  parts,  depending  on  the  size 
of  the  carriage  to  which  they  are  attached. 

The  principal  parts  are  (Hg.  55),  the  nave 
(2),  the  nave-bands  (3),  the  nave-box  (1),  the 
spokes  (4),  the  felloes  (5),  and  the  tire  (6). 

The  nave  constitutes  the  central  portion 
of  the  wheel,  and  distributes  the  pressure  of 
the  axle-arm  to  the  spokes.  It  is  generally 
made  of  a  single  piece  of  wood,  and  strength- 
ened by  four  iron  bands  called  the  nave- 
bands.  It  is  also  pierced  with  a  conical  hole  Fig- 55- 
for  the  axle-arm ;  and  to  diminish  wear  and  friction,  it 
is  lined  with  a  box  of  brass  or  cast-iron,  called  the  nave- 
box.  The  spokes  serve  to  transmit  the  pressure  of  the 
load  to  the  rim  of  the  wheel.  In  all  artillery  carriages 
there  are  seven  felloes  and  fourteen  spokes.  The  felloes 
are  the  wooden  segments  which  form  the  rim,  and  are 
joined  together  at  their  ends  by  wooden  pins,  or 
dowels.  The  tire  is  a  strong  band  of  iron,  shrunk 
tightly  around  the  felloes,  to  hold  them  together,  and 
protect  the  rim  from  wearing  away  by  contact  with  the 
ground. 


FEICTION.  221 

182.  Dish.  Tlie  spokes  are  fastened  to  the  nave  and 
felloes  by  means  of  mortices  and  tenons,  and  in  a  direc- 
tion oblique  to  the  axis  of  the  nave.  Thus  situated, 
they  constitute  the  elements  of  a  conical  surface,  which 
is  called  the  dish — the  principal  object  of  which  is  to 
give  stiffness  to  the  wheel,  and  enable  it  to  offer  greater 
resistance  to  the  lateral  vibrations  of  the  load,  in  pass- 
ing over  uneven  ground. 

The  height  of  the  dish  will  therefore  depend  on  the 
nature  of  the  ground ;  and  in  artillery  carriages,  which 
are  required  to  pass  over  a  great  variety  of  ground,  it 
is  about  two  inches. 

The  dish  gives  elasticity  to  the  wheel,  and  increases 
its  durability ;  it  permits  the  .  axle-tree  to  be  made 
shorter,  and  therefore  stronger ;  it  relieves  the  linch-pin 
of  a  certain  amount  of  pressure,  which  it  transfers  to 
the  shoulder- washer — the  wheel  is,  therefore,  less  liable 
to  come  off  in  travelling ;  for  a  given  length  of  axle-tree, 
it  allows  a  greater  width  of  carriage-body ;  and  finally, 
it  throws  the  mud  clear  of  the  carriage. 

The  stiffness  of  a  carriage- wheel  may  be  increased  by 
placing  every  alternate  mortice  in  the  nave  nearer  the 
shoulder  of  the  axle-tree :  this  gives  one  half  of  the 
spokes  a  greater  dish  than  the  other  half.  This  plan, 
however,  does  not  answer  for  artillery  carriages. 

183.  Friction.  The  object  of  a  carriage-wheel  is  to 
diminish  the  resistance  opposed  to  draught,  by  trans- 
ferring the  friction  from  the  ground  to  the  axle-arm. 

When  a  carriage  is  at  rest,  the  lowest  element  of  the 
axle-arm  is  supported  on  the  bottom  of  the  nave-box. 
To  set  the  carriage  in  motion,  the  friction  along  the 
elements  of  contact,  arising  from  the  weight  of  the  car- 


222  ARTILLERY    CARRIAGES. 

riage,  must  be  overcome,  and  the  axle-arm  must  rise  in 
the  nave-box  as  though  it  were  moving  up  an  inclined 
plane  tangent  to  the  surface  of  the  box.  When  this  is 
done,  the  weight  of  the  loaded  axle-arm  causes  the 
wheel  to  revolve  around  the  point  of  contact  with  the 
ground,  and  the  constant  repetition  of  these  conditions 
produces  motion. 

Let  P  be  the  weight  resting  on  the  element  of  con- 
tact; p  the  weight  of  the  wheel;  Xthe  force  necessary 
to  produce  motion ;  r  the  radius  of  the  box;  and/ the 
co-efficient  of  friction  between  the  arm  and  box.  When 
the  wheel  is  well  greased,  this  co-efficient  is  about  0.180. 

To  determine  the  force  acting  parallel  to  the  ground 
which  will  move  the  wheel,  we  have  the  resultant  of 
P  and  JT,  equal  to  VP2-\-X*,  and  the  friction  arising 
from  it,  equal  to  fVP2+X2.  The  pressure  on  the 
ground  is  P-\-p;  and  if  the  wheel  slips,  the  friction  on 
the  ground  will  be  F(P-\-p),  F  being  the  co-efficient 
of  friction.  The  points  of  these  resistances,  being  at 
the  distances  r  and  R  from  the  centre  of  rotation,  re- 
spectively, they  will  counteract  each  other  when 

rf\/P2~+JP=FR(P+p). 

If  the  wheel  turns,  there  is  no  slipping  on  the  ground, 
and 

frfP*+X'<FIl(F+p), 

from  which  it  results  that 


Vpi+JT_      frp 
R  VR2-f2^ 

So  long  as  the  wheel  turns,  the  draught  is  not  af- 
fected by  the  friction  on  the  ground,  since  the  value  of 
X  is  independent  of  F;  but  if  F  becomes  so  small 


ROLLING-FRICTION.  223 


that  frvP2-\-X2  becomes  equal  to  or  greater  than 
FM{P-\-p),  the  wheel  will  no  longer  turn,  but  slide  as 
the  runner  of  a  sled.  This  occurs  on  ice,  or  when  the 
wheels  are  locked;  in  which  case  the  draught  is  pro- 
portional to  the  friction  on  the  ground. 

From  the  expression  for  the  value  of  X  we  see  that 
the  resistance  which  a  wheel  offers  to  motion,  increases 
with  the  radius  of  the  axle-arm,  and  decreases  with  the 
radius  of  the  wheel. 

When  the  radii  are  nearly  equal,  the  wheel  becomes 
a  roller — a  machine  much  used  in  modifying  the  fric- 
tion of  fortress  carriages. 

184.  Rolling-friction.  In  the  theoretical  expression 
of  the  force  necessary  to  move  a  wheel,  rolling-friction 
has  been  omitted,  as  it  is  very  small  when  the  wheel  is 
inelastic,  and  the  ground  is  very  hard.  The  experi- 
ments of  Coulomb  show  that  this  kind  of  friction  does 
not  increase  the  draught  of  an  artillery  carriage  more 
than  2  j-  lbs. 

When  the  wheel  penetrates  the  ground,  it  will  expe- 
rience the  same  resistance  as  though  it  were  moving 
upon  an  inclined  plane  whose  inclination  increases  with 
the  depth  of  penetration;  and  Edge  worth  found,  in  ex- 
periments with  two-horse  carriages,  that  the  force  neces- 
sary to  move  a  wheel  is  six  times  greater  than  the  the- 
oretical force.  This  difference  arises  from  the  compres- 
sibility of  the  soil,  and  the  flexibility  of  the  wheel.  On 
railroads,  where  the  wheels  and  track  are  made  of  iron, 
the  actual  and  the  theoretical  draught  are  very  nearly 
the  same ;  and  on  the  best  roads  it  is  about  five  times 
more  than  on  a  railroad. 

The  depth  of  the  rut,  or  track,  made  by  a  wheel,  may 


224  ARTILLERY    CARRIAGES. 

be  reduced  by  making  the  felloes  broader ;  this  increase 
will  also  cause  a  wheel  to  pass  more  easily  over  rough 
ground.  Rumford  found  by  experiment  that  a  7 -inch 
felloe  required  one-tenth  more  tractile  force  than  one  of 
12  inches  breadth,  on  a  pavement,  one-twelfth  on  a  hard 
road,  and  one-seventh  on  a  sandy  road. 

185.  Size  of  wheel.  The  saving  of  tractile  force  arising 
from  increasing  the  diameter  of  a  carriage-wheel,  is  lim- 
ited by  the  height  of  the  horse,  for  if  the  centre  of  the 
nave  be  higher  than  his  shoulders — the  point  at  which 
the  traces  are  attached — the  line  of  traction  will  be  in- 
clined downward,  and  if  he  be  moving  up  hill,  or  on 
level  ground,  the  vertical  component  of  the  tractile  force 
will  increase  the  friction  of  the  wheel,  and  diminish  the 
hold  of  the  horse  upon  the  ground.  If  he  be  moving 
down  hill,  the  same  cause  diminishes  the  friction  of  the 
wheels,  and  consequently  increases  the  difficulty  of  hold- 
ing back. 

Large  wheels  surmount  ordinary  obstacles  more 
easily  than  small  ones,  and .  penetrate  less  into  yielding 
ground. 

Weight  of  wheel.  The  wheels  of  gun-carriages  should 
be  as  light  as  possible,  to  prevent  the  axle-tree  from 
being  bent  in  the  first  instant  of  the  recoil,  before  their 
inertia  is  overcome. 

186.  Kinds.  To  make  it  practicable  to  replace  broken 
wheels  in  the  field,  there  should  be  as  few  kinds  as  pos- 
sible for  each  service.  In  the  field  service  there  are  two 
sizes,  called  Nos.  1  and  2 ;  and  in  the  siege  service  but 
one.  The  No.  2  wheel  is  stronger  than  No.  1,  and  is 
used  on  the  heaviest  carriages.  Both  wheels,  however, 
have  the  same  height  (58  inches)  and  the  same  size  of 


GUN-CARRIAGES.  225 

nave-box,  that  they  may  be  interchanged  if  necessary. 
The  siege  wheel  is  60  inches  in  diameter. 

GUN-CARKIAGES. 

187.  General  conditions.  Gun-carriages  are  designed 
to  transport  cannon  from  one  point  to  another,  and  to 
support  them  when  fired.  A  suitable  gun-carriage, 
therefore,  should  allow  the  piece  to  be  easily  and 
promptly  pointed  in  the  direction  of  its  object;  it 
should  be  capable  of  being  served  by  the  smallest  num- 
ber of  men,  and  transported  with  the  greatest  ease ;  its 
recoil,  under  fire,  should  be  restrained  within  suitable 
limits;  and  it  should  have  sufficient  strength  and  sta- 
bility to  resist  overturn  or  injury  from  the  greatest 
service-charge. 

The  injury  to  the  carriage  arising  from  the  recoil  of 
the  piece,  increases  with  the  square  of  the  velocity  of 
the  recoil,  which  is  dependent  on  the  relation  between 
the  weight  of  the  carriage  and  the  weight  of  the  piece. 
Generally  speaking,  the  piece  should  be  heavier  than 
the  carriage. 

188.  Principal  parts.  Artillery  carriages,  like  the 
cannon  which  they  support,  are  classified  into  field, 
mountain,  prairie,  -siege,  and  sea-coast  carriages.  The 
sea-coast  carriages  not  being  required  for  the  transporta- 
tion of  their  pieces,  differ  materially  from  the  others  in 
their  construction. 

The  principal  parts  of  all  other  art  llery  carriages  (fig. 
i)6)  are,  the  stock  (1),  the  cheeks  (2),  the  axle-tree  (3), 
the  wheels  (4),  and  the  elevating  screw  (5). 

The  stock.     The  stock  is  a  long  rectangular  piece  of 

15 


226 


ARTILLERY    CARRIAGES. GUN-CARRIAGES. 


Fig.  56. 


wood,  the  front  end  of  which  is  attached  to  the  axle- 
tree,  while  the  rear  end  rests  npon  the  ground  when  the 
piece  is  fired,  to  form,  with  the  wheels,  the  three  neces- 
sary points  of  support. 

When  the  carriage  is  in  travelling  condition,  the  stock 
connects  the  front  and  rear  wheels,  and  constitutes  the 
basis  of  the  carriage-body.  It  is  employed  as  a  point 
of  support  for  the  elevating  screw,  and  to  give,  with  the 
assistance  of  a  handspike  inserted  in  its  rear  end,  the 
proper  direction  to  the  piece  in  aiming. 

The  cheeks.  The  cheeks  are  two  thin  but  strong 
pieces  of  wood,  attached,  one  to  each  side  of  the  head- of 
the  stock,  to  sustain  the  trunnions  of  the  piece.  The 
notches  into  which  the  trunnions  fit  are  lined  with  iron 
plates,  called  the  trunnion-bed  plates. 

The  axle-tree.  The  axle-tree  is  composed  of  two  parts 
— the  axle-tree  proper,  which  is  made  of  wrought  iron, 
and  the  wooden  body,  which  encases  all  the  iron  portion 
between  the  wheels,  in  such  a  manner  as  to  distribute 
the  pressure  of  the  head  of  the  stock  and  cheeks  uniform- 
ly over  it,  and  prevent  it  from  being  bent  by  the  shock 
of  the  discharge. 

The  extremities  of  the  axle-tree,  or  arms,  are  accurate- 
ly turned  to  a  conical  shape  to  fit  the  nave-boxes.     The 


GUN-CARRIAGES.  227 

conical  shape  gives  lightness  and  stiffness  to  the  arm, 
and  facilitates  putting  on  the  wheel.  The  lower  ele- 
ments of  the  arms  being  horizontal,  the  pressure  is  nor- 
mal to  the  surface  of  the  arm,  and  there  is  no  undue 
tendency  of  the  wheel  to  slip  off. 

The  wheel  is  secured  by  a  linch-pin ;  and  the  ex- 
tremities of  the  nave  are  protected  from  wear  by  two 
rings  of  iron,  called  the  linch-washer  and  the  shoulder- 
washer. 

Nave-box.  The  inner  surface  of  the  nave-box  is  en- 
larged about  its  middle  portion,  forming  a  recess,  or 
receptacle,  for  the  lubricating  material. 

So  long  as  the  wheel  is  kept  well  greased,  there  is 
but  little  difference  between  the  friction  and  wear  of 
brass  and  cast-iron  nave-boxes,  but  when  the  grease  is 
exhausted,  there  is  a  superiority  in  favor  of  brass.  Cast 
iron,  however,  is  most  generally  employed,  on  account 
of  its  cheapness. 

The  relation  between  the  draught  of  greased  and  un- 
greased  wheels,  is  determined  by  experience  to  be, 

WITH   OREASE.       WITHOUT   GREASE. 

'  "  i   txt„~j „_i„  a 

On  horizontal' ground, 
Inclined  ground,  1-24, 


Irons.  The  remaining  iron  parts  of  a  gun-carriage 
may  be  divided  into  three  classes,  viz.: — 1st.  Those 
which  serve  to  connect  and  strengthen  the  principal 
parts,  before  enumerated,  as  the  assembling-bolts,  straps, 
and  bands.  2d.  Those  which  protect  the  wood- work 
from  wearing  away  at  certain  points,  as  the  trunnion- 
plates  (6),  the  trail-plate  and  shoe  (7),  and  the  wheel- 


Wooden  axle-trees, 

65 

108 

Iron               " 

56* 

61| 

Wooden        " 

96* 

162j 

Iron               " 

95 

100 

228 


ARTILLERY    CARRIAGE3.- 


UN-CARRIAGES. 


J* 


guard  plate  (8).  3d.  Those  employed  to  fasten  the  im- 
plements to  the  carriage.  The  number  of  the  pieces  of 
the  last  class  depends  upon  the  character  of  the  service 
to  which  the  piece  belongs.  In  the  field,  mountain,  and 
prairie  carriages,  all  the  implements  necessary  for  the 
use  of  the  piece  are  carried  upon  the  carriage.  The 
implements  of  the  siege-carriage  are  carried  in  store- 
wagons. 

189.  Force§  acting  on  a  gun-carriage.  As  the  axis  of 
the  bore  intersects  the  axis  of  the  trunnions,  the  entire 
force  of  the  charge,  acting  on  the  bottom  of  the  bore,  is 
communicated  to  the  carriage  at  the  trunnion-beds.  The 
carriage  being  constructed  symmetrically  with  regard  to 
the  axis  of  the  piece,  we  are  at  liberty,  in  the  following 
discussion,  to  suppose  that  the  wheels,  trunnion-beds, 
and  trail,  are  all  situated  in  the  same  plane,  and  that 
the  resultant  of  the  force  of  the  charge  is  applied  at  the 
point  where  the  axis  of  the  trunnions  pierces  this  plane. 
The  action  of  the  force  of  the  charge  is  to  move  the 
carriage  along  the  surface  of  the  ground  (supposed  to 
be  horizontal),  to  press  the  wheels  and  trail  upon  the 
ground,  and  to  rotate  the  carriage  around  the  point  of 
contact  of  the  trail  with  the  ground. 

Let  v  be  the  position 
of  the  axis  of  the  trun- 
nions, and  mv  represent 
the  amount  and  direction 
of  the  force  of  the  recoil, 
and  0  the  angle  of  fire.      Let  L  be  the  point  of  contact 
of  the  trail  and  ground,  a  the  distance  of  this  point  frcm 
the  trunnions,  a  the  angle  which  the  line  joining  these 
two  points  makes  with  the  horizontal,  G  the  position 


GUN-CARRIAGES.  229 

of  the  centre  of  gravity,  and  p  its  horizontal  distance 
from  the  point  L. 

If  mv  be  the  force  of  the  recoil,  li  and  C  the  pressures 
exerted  by  it  upon  the  wheel  and  trail,  respectively,  we 
have  the  relation 

mv  sin.  d-=P-\-C. 

The  horizontal  component  acts  to  overcome  the  fric- 
tion of  the  wheel  and  trail,  and  to  set  the  carriage  in 
motion.  By  making  f  the  unit  of  friction,  and  MV  the 
quantity  of  motion  impressed  on  the  carriage,  we  have 

mv  cos.  e=f(C+B)+M V; 
or,  by  substituting  the  value  of  R-\-C  from  the  above 
equation,  and  solving  with  reference  to  V,  we  have 

tt_  mv  (cos.<9  — /sin.0  V 
~~M~ 

which  is  the  velocity  of  recoil. 

As  the  unit  of  friction  of  the  wheel  and  trail  are  not 
exactly  the  same,  the  foregoing  equation  will  not  give  a 
strictly  correct  value  for  V  for  field  and  siege  carriages, 
but  it  will  be  correct  for  fortress-carriages  and  mortar- 
beds,  which  do  not  move  on  wheels,  in  recoil. 

The  force  mv  also  acts  to  rotate  the  carriage  around 
the  point  L  with  an  effect  proportional  to  its  lever  arm 
Ld,  which  is  equal  to  a  sin.  dvL  ;  but  sin.  dvL= sin. 
(180°  —  («+#),)  and  the  moment  of  the  force  of  the 
charge,  with  reference  to  the  trail,  is  mva  sin.  (180°— 

This  moment  being  equal  to  the  moment  of  the  weight 
of  the  piece,  and  the  moment  of  the  quantity  motion  im- 
pressed upon  the  carriage,  or  _P,  we  have 

mva  sin.  (180°  —  a  —  e)=  Wp+P. 


230  ARTILLERY    CARRIAGES. LIMBER. 

Wk2W 

But  JP= ;  Tc  being  the  radius  of  gyration  of  the 

I/ 

gun  and  carriage  taken  with  reference  to  the  trail,  g  the 
force  of  gravity,  and  w  the  angular  velocity  of  the  gun 
and  carriage. 

Substituting  this  value  of  P  in  the  above  equation, 
and  reducing,  we  have 


i©> 


mva  sin  (ISO0— a— e)—  Wp 


With  this  relation  we  can  discuss,  by  giving  different 
values  to  0,  «,  a,  andj9,  the  effect  of  the  angle  of  fire, 
length  of  trail,  position  of  trunnions,  and  centre  of 
gravity,  on  the  stability  of  the  carriage,  or  the  resistance 
which  it  offers  to  overturning  by  the  force  of  the  charge 
acting  at  the  centre  of  the  trunnions. 

LIMBER. 

190.  Object.  Thus  far  a  gun-carriage  has  been  con- 
sidered only  in  relation  to  the  fire  of  the  piece,  or  as  a 
ttvo- wheel  carriage.  To  suit  it  to  the  easy  and  rapid 
transportation  of  its  load,  it  must  be  converted  into  a 
four- wheel  carriage,  which  is  done  by  attaching  it  to  an- 
other two- wheel  carriage  called  a  limber. 

191.  Construction.  The  field-limber  is  composed 
(see  fig.  58),  of  an  axle- 
tree  (1),  a  fork  (2),  two 
hounds  (3  3),  a  splinter- 
bar  (4),  two  foot-boards 
(5  5),  a  pole  (6),  a  pintle- 
hook  and  key  (7  ),  twojwfe- 
yokes(8),an&apole-pad(9).  Fig.  58. 


•- 


CONSTRUCTION.  231 

A  side  view  of  this  limber  is  also  shown  in  fig.  59, 
together  with  the  manner  of  attaching  the  rear  carriage 
to  the  pintle-hook. 

The  axle-tree.  The  limber  axle-tree  is  made  of  iron, 
imbedded  in  a  body  of  wood,  as  in  the  case  of  the  gun- 
carriage. 

The  fork.  The  fork  constitutes  the  middle  portion 
of  the  limber,  and  is  the  portion  to  which  the  pole  is 
attached.  It  is  formed  of  a  single  piece  of  wood,  one 
end  of  which  is  mortised  into  the  axle-body,  and  secured 
by  the  pintle-hook  bolts,  and  the  other  is  cut  into  the 
shape  of  a  fork,  to  receive  the  tenon  of  the  pole. 

The  hounds.  The  hounds  are  two  wooden  rails  which 
are  bolted  to  the  axle-body  and  splinter-bar.  They 
serve  to  support  the  ends  of  the  limber-chest  and  foot- 
boards, and  also  to  transmit  the  draught  of  the  horses 
to  the  axle-tree.  The  chest  is  secured  by  a  stay-plate, 
situated  at  the  bottom  of  the  cut  in  the  fork,  and  two 
stay-pins,  which  pass  through  holes  near  the  rear  ends 
of  the  hounds. 

The  splinter-bar.  The  splinter-bar  is  a  piece  of  wood 
placed  cross- wise  with  the  pole,  and  is  firmly  secured  to 
the  fork  and  hounds.  It  has  four  hooks,  to  which  the 
traces  of  the  wheel  horses  are  attached. 

The  pole.  The  pole,  or  tongue,  is  employed  to  regu- 
late the  motion,  and  give  direction  to  the  carriage.  The 
point  of  attachment  of  the  rear  carriage  being  near  the 
axle-tree,  and  there  being  no  sweep-bar,  the  weight  of 
the  pole  is  mostly  supported  by  the  collars  of  the  rear 
horses;  it  should  therefore  be  made  of  strong,  light 
wood — ash  is  generally  used  for  this  purpose. 

As  the  pole  is  liable   to  be  broken  in  service,  the 


232  ARTILLERY    CARRIAGES. LIMBER. 

method  of  attaching  it  to  the  fork  should  be  such  that 
the  fragments  can  be  promptly  removed,  and  a  new  pole 
inserted. 

The  foot-hoards.  The  foot-boards  are  secured  to  the 
fork  and  hounds  in  a  proper  position  for  the  feet  of  the 
cannoniers  to  rest  upon,  while  riding  upon  the  limber- 
chest. 

The  pintle-hook.  The  pintle-hook  is  a  stout  iron  hook 
firmly  fastened  to  the  rear  of  the  axle-tree,  for  the 
purpose  of  attaching  the  rear  carriage.  This  mode 
of,  attachment  is  simple,  strong,  and  flexible — qualities 
which  are  essential  to  rapid  movements  and  great  en- 
durance. The  point  of  the  hook  is  perforated  with  a 
hole  for  the  pintle-key,  which  prevents  the  carriages  from 
separating  while  in  motion. 

In  the  old  system  of  field-carriages,  the  operation  of 
limbering  and  unlimbering  was  so  difficult,  that  a  rope, 
called  a  "prolonge,"  was  used  to  connect  the  gun-car- 
riage and  limber,  in  action.  This  implement  is  still 
retained,  but  the  same  necessity  does  not  exist  for 
using  it. 

192.  Turning.  All  field-carriages  should  admit  of 
being  turned  in  the  shortest  possible  space.  This  de- 
pends upon  the  size  of  the  front  wheels,  the  distance 
between  the  front  and  rear  axle-trees,  the  position  of  the 
pintle,  and  the  thickness  of  the  stock  at  the  point  where 
the  front  wheel  strikes  it.  Notwithstanding  that  the 
front  wheels  are  made  higher  in  the  present  system  of 
field-carriages  than  the  Gribeauval  system,  which  pre- 
ceded it,  the  carriages  of  the  former  have  greater  facility 
of  turning,  in  consequence  of  the  diminished  thickness 
of  the  stock. 


LOCKING    WHEELS.  233 

193.  Track.  By  track  is  understood  the  distance  be- 
tween the  furrows  formed  by  the  wheels  in  the  ground. 

It  is  important  that  the  track  should  be  the  same  for 
all  carriages  likely  to  travel  the  same  road,  in  order  that 
the  wheels  of  one  carriage  may  follow  in  the  furrows 
formed  by  those  of  its  predecessor,  and  thereby  prevent  a 
loss  of  tractile  force.  The  track  of  artillery  carriages  is 
5  feet,  and  the  extreme  length  of  the  axle-tree  is  6^- 
feet  for  field,  and  6}  feet  for  siege-carriages. 

194.  i,oad.  As  the  forward  wheels  "of  a  carriage  form 
the  ruts,  they  should  support  a  smaller  portion  of  the 
load  than  the  rear  wheels:  in  field-carriag*es,  the  pro- 
portion is  as  two  to  three. 

195.  Length  of  stock.  The  length  of  the  stock  deter- 
mines the  distance  between  the  front  and  rear  wheels. 
The  longer  this  distance  is,  the  greater  will  be  the  space 
required  to  turn  the  carriage  in,  and  the  greater  will  be 
the  effort  necessary  to  pull  the  carriage  over  a  sharp 
elevation  of  the  ground. 

196.  Wheels.  All  wheels  of  an  artillery  carriage 
should  be  of  the  same  height,  to  permit  of  interchange, 
and  to  make  the  line  of  traction  parallel  to  the  ground. 

197.  Locking  Wheels,  The  work  of  holding  back  a 
carriage,  on  descending  ground,  devolves  on  the  pole- 
horses.  When  the  descent  is  very  steep,  and  the  load 
large,  they  are  relieved  of  a  portion  of  this  work  by 
attaching  a  chain  to  one  of  the  rear  wheels,  in  such  a 
manner  as  to  prevent  it  from  turning,  and  thereby 
changing  the  friction  on  the  axle-arm  to  friction  on  the 
ground.  In  field-carriages,  one  end  of  the  locking-chain 
is  secured  to  the  stock  by  the  assembling-bolt,  and  the 
other  is  passed  around  the  felloe,  and  secured  to  itself 


234  ARTILLERY    CARRIAGES. FIELD    CARRIAGES. 

by  a  key.  In  siege-carriages,  where  the  load  is  much 
heavier,  a  shoe  is  attached  to  the  chain,  upon  which  the 
wheel  rides.  This  prevents  the  tire  from  being  worn 
and  the  wheel  from  being  strained ;  at  the  same  time, 
the  operation  of  locking  and  unlocking  can  be  per- 
formed without  stopping  the  carriages. 

FIELD-CARRIAGES. 

198.  Kind§.  The  carriages  pertaining  to  the  field 
service,  are  the  gun-carriage,  the  caisson,  the  travelling- 
forge,  and  the  battery -ivagon.  The  same  limber  is  used 
for  all  the  field-carriages,  with  the  exception  of  the  in- 
terior arrangement  of  the  chest,  which  is  adapted  to  the 
kind  of  the  carriage  to  which  the  limber  is  attached. 

199.  Gun-carriage§.  Field-carriages  are  characterized 
by  great  lightness,  strength,  and  mobility.     They  are, 

The  6-pdr.  gun  and  1 2-pdr.  howitzer  carriage. 

The  12-pdr.  gun  (light)  and  the  1\-pdr.  howitzer  car. 
riage. 

The  12-pdr.  gun  (heavy)  and  the  32-pdr.  howitzer 
carriage* 

These  carriages  are  of  similar  construction,  the  only 
difference  being  in  the  size  and  strength  of  the  several 
parts.  The  first  is  mounted  on  light,  or  No.  1  wheels, 
and  the  second  and  third  on  No.  2,  or  heavy  wheels. 
Attached  to  each  carriage  are  the  following  named  im- 
plements, viz.,  two  rammers  and  sponges,  two  trail- 
handspikes,  one  worm,  one  sponge-bucket,  one  tar-bucket, 
one  watering-bucket. 

*  The  10-pdr.  Parrott  and  the  3-in.  rifle  guns  are  mounted  on  the  6-pdr.  carriage, 
and  the  20-pdr.  Parrott  rifle-gun  is  mounted  on  the  12-pdr.  (heavy)  carriage. 


caisson.  235 

200.  €ais§ou.  The  caisson  is  used  to  transport  ammu- 
nition ;  and  in  light  field-batteries,  there  is  one  caisson  to 
each  piece,  in  heavy  batteries  there  are  two.  The  am- 
munition is  contained  in  three  chests — two  mounted  on 
the  body,  and  one  on  the  limber.  The  number  of  rounds 
for  each  chest  varies  with  the  calibre  of  the  piece,  as 
follows,  viz. : 

6-pdr.  gun,  and  3-inch  rifle-gun,         .     50 

12-pdr.  gun,  ....         32 

12-pdr.  howitzer,      .         .         -         .39 

24-pdr.  howitzer,  .         .         .         .         23 

32-pdr.  howitzer,       .         -         .         .15 

The  whole  number  of  rounds  for  each  piece  may  be 

ascertained  by  multiplying  the  above  numbers  by  four. 

The  caisson  is  composed  of  a  body,  and  a  limber.  See 

fig.  59.     The  body  is  composed  of  one  middle  and  two 

side  rails  (1),  one  stock  (2),  and  one  axle-tree  (3).     It 


Fig    59. 

carries  two  ammunition-chests  (4,  5),  a  spare  wheel  (6), 
which  fits  upon  an  iron  axle-arm  attached  to  the  rear 
end  of  the  middle  rail,  one  spare  pole  (7),  fastened  to 
the  under  side  of  the  stock,  and  a  spare  handspike.  The 
spare  articles  are  needed  to  replace  broken  parts. 

The  caisson  also  carries  a  felling-axe,  shovel,  and  pick- 
axe, to  remove  obstructions,  repair  roads,  &c,  a  tarpau- 


236  ARTILLERY    CARRIAGES. FIELD    CARRIAGES. 

lin  strapped  on  to  the  limber-chest,  a  tar-bucket,  and  a 
watering-bucket. 

201.  Travelling-forge.  The  travel  ling-forge  is  a  com- 
plete blacksmith's  establishment,  which  accompanies 
the  battery  for  the  purposes  of  making  repairs  and  shoe- 
ing horses.  It  consists  of  a  body,  upon  which  is  con- 
structed the  bellows-house,  &c,  and  the  limber,  which 
supports  the  stock,  in  transportation.  The  body  (see 
fig.  60)  is  composed 
of  two  rails  (1),  a 
stock  (2),  and  an 
axle-tree  (3).  The 
bellows-house  is  di- 
vided into  the  bel- 
lows-room (4),  and  "  Fig.  60. 
the  iron-room  (5).  Attached  to  the  back  of  the  house 
is  the  coal-box  (6),  and  in  front  of  it  is  the  fire-place  (7). 
From  the  upper  and  front  part  of  the  bellows,  an  air- 
pipe  (8)  proceeds  in  a  downward  direction  to  the  air- 
box,  which  is  placed  behind  the  fire-place.  The  vise  (9) 
is  permanently  attached  to  the  stock,  and  the  anvil, 
when  in  use,  is  supported  on  a  stone  or  log  of  wood, 
and  when  transported  is  carried  on  the  hearth  of  the 
fire-place.  The  remaining  tools  are  carried  in  the  lim- 
ber-chest. When  in  working  order,  the  point  of  the 
stock  is  supported  by  a  prop  (10). 

202.  Battery- wagon.  The  battery- wagon  is  employed 
to  transport  the  tools  and  materials  for  repairs.  Among 
the  tools  are  those  for  carriage-makers,  saddlers,  armor- 
ers, and  laboratorians'  use,  scythes  and  sickles  for  cut- 
ting forage  and  spare  implements  for  the  service  of  the 
piece. 


MOUNTAIN    CARRIAGE.  237 

The  body  (1)  of  the  battery-wagon  (see  fig.  61)  is  a 
large  rectangular  box,  covered  with  a  roof  of  painted 


Fig.  61. 

canvas ;  and  to  the  back  part  is  attached  a  rack  (2)  for 
carrying  forage.  The  bottom  of  the  body  is  formed  of 
one  middle  and  two  side  rails,  resting  on  a  stock  and 
axle-tree,  as  in  the  travelling-forge. 

The  tools  and  materials  of  the  battery-wagon  are 
carefully  packed  in  the  manner  prescribed  by  the  Ord- 
nance Manual,  in  order  that  no  difficulty  may  be  expe- 
rienced in  finding  a  particular  article  when  wanted. 
The  smaller  articles  are  carried  in  boxes  properly  let- 
tered and  numbered. 

The  travelling-forge  and  battery-wagon  are  not  con- 
fined to  the  service  of  field-batteries,  but  are  used  with 
siege  and  sea-coast  carriages,  as  occasion  may  require. 

MOUNTAIN-CAKRIAGE. 

203.  Requirements,  &c.  The  mountain-howitzer  car- 
riage should  be  light  enough  to  be  carried  on  the  back 
of  a  pack  animal,  and  the  axle-tree  should  be  short 
enough  to  permit  it  to  pass  through  very  narrow  de- 
files. 

It    differs    in    construction    from    the    field-carriage, 


238  ARTILLERY    CARRIAGES. PRAIRIE. 

inasmuch  as  the  stock  and  cheeks 
(1)  (fig.  62)  are  formed  of  the  same 
piece,  by  hollowing  out  the  head  of 
the  stock.     The  wheels  are  thirty- 
's- 62-  eight  inches  in  diameter,  and  the 
axle-tree  is  made  of  wood,  the  arms  being  protected 
from  wear  by  skeans,  or  strips  of  iron. 

The  distance  between  the  wheels  is  about  equal  to 
their  diameter.  It  is  arranged  for  draught  by  attaching 
a  pair  of  shafts  to  the  trail.  The  pack-saddle  and  its 
harness  are  constructed  to  carry  severally,  the  howitzer 
and  shafts,  the  carriage,  or  two  ammunition  chests,  or  it 
enables  an  animal  to  draw  the  carriage,  with  the  howit- 
zer mounted  upon  it. 

A  portable  forge  accompanies  each  mountain  battery, 
and  is  so  constructed  that  it  can  be  enclosed  in  two 
chests,  and  carried,  with  a  bag  of  coal,  upon  the  pack- 
saddle. 

PRAIRIE-CARRIAGE. 

204.  Description,  &c.  The  prairie-carriage  is  designed 
to  carry  the  mountain-howitzer,  and  is  similar  to  the 
mountain-carriage  in  the  form  and  combination  of  its 
parts ;  but  being  exclusively  intended  for  draught,  the 
axle-tree  is  made  of  iron,  the  wheels  are  made  higher, 
and  the  distance  between  them  greater  than  in  the 
mountain-carriage.  It  has  a  limber,  and  is  drawn  by 
two  horses  abreast,  as  in  field-carriages.  The  ammuni- 
tion is  packed  in  mountain  ammunition  chests,  two  of 
which  are  carried  on  the  limber,  and  the  remainder  in 
a  covered  cart,  of  peculiar  construction,  or  packed  on 
animals,  as  in  the  mountain  service. 


SIEGE-CARRIAGES.  239 


SIEGE-CAKRIAGES. 

205.  Kiiid§  of.  The  siege-carriages  are 

The  24rpdr.  gun  and  8-inch  howitzer  carriage. 

The  18  -pdr.  gun-carriage. 

The  12-pdr. 

The  mortar-wagon. 

The  limber. 

The  mortar-bed. 

206.  Gun-carriage.  The  construction  of  the  siege- 
gun  carriage  is  similar,  in  most -of  its  details,  to  the  field- 
gun  carriage.  It  differs,  however,  in  the  greater  strength 
of  the  parts,  and  in  the  mode  of  attaching  to  the  lim- 
ber, and  by  the  absence  of  the  parts  used  for  carrying 
the  implements. 

The  position  of  the  trunnion-beds  is  such  that  when 
the  carriage  is  limbered  up,  the  weight  of  the  piece  is 
thrown  too  much  on  the  rear  wheels  for  convenience  of 
transportation;  another   set  of  trunnions  is  therefore 


Fig.  63. 


formed  at  the  rear  end  of  the  cheeks,  by  enlarging  the 
heads  of  the  cheek-bolts,  and  the  piece  is  shifted  to  them 
in  transportation.     They  are  called  the  "  travelling  trun- 


240  ARTILLERY    CARRIAGES. SIEGE-CARRIAGES. 

nions?  See  (1)  fig.  63.  The  breech  of  the  piece  rests 
in  a  groove  formed  in  a  block  of  wood,  called  the  "  bol- 
ster11 (2) ;  and  the  elevating  screw  is  disposed  of  by 
reversing  it  in  its  nnt.  To  prevent  it  from  unscrewing 
by  the  motion  of  the  carriage,  one  of  the  handles  is 
slipped  through  a  leather  loop  attached  to  the  under 
side  of  the  stock. 

207.  Limber.  The  same  kind  of  limber  is  used  for  all 
siege-carriages.  It  is  composed  of  a  fork  (4),  the  pole 
(5),  the  axle-tree  (6),  the  pintle  (7),  the  hounds  (8),  the 
splinter-bar  (9),  and  the  friction-circle  (10),  one  end  of 
which  is  only  represented  in  the  figure. 

The  fork  constitutes  the  main  part  of  this  carnage, 
and  to  it  are  attached  the  pintle,  the  pole,  the  splinter- 
bar,  the  axle-tree,  and  the  friction-circle. 

As  this  carriage  is  not  subjected  to  the  shock  of 
firing,  the  axle-tree  is  not  imbedded  in  wood  to  give  it 
stiffness,  as  in  the  gun-carriage. 

The  pintle  is  placed  far  enough  in  rear  of  the  centre 
of  the  axle-tree  to  enable  the  weight  of  the  stock  of  the 
gun-carriage  to  act  as  a  counterpoise  to  the  pole,  and 
give  it  steadiness  when  the  carriage  is  in  motion.  The 
friction-circle  acts  as  a  sweep-bar  for  the  shoe  of  the  trail 
to  rest  upon  when  the  limber  turns  around  its  pintle. 
The  attachment  of  the  two  carriages  is  secured  by  a 
lashing  chain  and  hook. 

208.  Mortar- wagon.  The  mortar- wagon  is  employed 
to  transport  siege  projectiles,  mortars  and  their  beds,  and 
spare  guns. 

It  is  composed  of  a  limber  and  body.  The  body  con- 
sists of  two  middle-rails,  united  so  as  to  form  the  stock, 
and  two  side-rails.     These  pieces  rest  upon  the  axle-tree, 


PLATFORM.  241 

and  are  strongly  connected  together  by  cross  pieces  of 
wood  and  straps  of  iron.  At  the  rear  of  the  body  is 
placed  a  windlass,  which  aids  in  mounting  guns  and 
mortars.  Stakes  are  placed  around  the  sides  of  the 
body,  to  sustain  the  side  and  end  boards  which  are  used 
in  transporting  projectiles. 

209.  Mortar-bed.  The  lightness  of  the  mortar,  and 
the  high  angle  under  which  it  is  fired,  render  it  unsafe 
to  be  fired  from  a  carriage ;  it  is,  therefore,  mounted  on 
a  bed,  which  rests  directly  on  a  platform. 

The  siege  mortar-bed  is  made  of  a  single  piece  of  cast 

iron,  of  a  form  shown  in 
fig.  64*  The  different 
parts  are,  the  cheeks  (1), 
and  the  front  and  rear 
transoms  (2,  3),  shown  in 
Fig-  64-  broken  lines.     To  the  front 

transom  is  attached  a  wooden  bolster,  upon  which  rests 
the  quoin,  or  wedge,  used  in  sustaining  the  piece  at  the 
proper  elevation.  From  the  outer  sides  of  the  cheeks 
project  four  pieces,  called  manoeuvring  bolts,  to  which 
handspikes  are  applied  in  moving  the  bed,  when  point- 
ing the  piece. 

210.  Platform.  To  insure  accuracy  of  fire  with  heavy 
guns  and  mortars,  it  is  absolutely  necessary  that  their 
carriages  and  beds  should  rest  upon  solid  and  sub- 
stantial platforms. 

The  platforms  for  siege-pieces,  being  transported  with 
an  army,  should  have  the  greatest  lightness,  compatible 
with  strength  to  endure  the  shocks  of  long-continued 

*  The  beds  for  all  the  new-pattern  mortars  are  made  of  wrought  iron — boiler 
plate  and  rolled  bars  fastened  together  by  screw-bolts. 
16 


242  ARTILLERY    CARRIAGES. —  SIEGE    CARRIAGES. 

firing.  They  are  composed  of  a  certain  number  of  pieces 
of  wood ;  and  in  order  that  these  pieces  may  be  carried 
on  the  backs  of  soldiers  from  the  depot  to  the  battery, 
the  weight  of  the  heaviest  piece  should  not  exceed  fifty 
pounds.  Siege-platforms  consist  of  sleepers  (1),  (fig. 
65),  and  deck-plank  (2).  The  general  direction  of  the 
sleepers  is  parallel  to  the  axis  of  the  piece,  and  the 
deck-plank  at  right  angles  to  it;  this  disposition  of 
the  parts  offers  the  greatest 
resistance  to  the  recoil  of  the 
carriage.  The  deck-planks  are 
fastened  together  at  their 
edges  by  dowels ;    the  outer  Fig.  65 

planks  are  secured  by  iron  eye-pins,  one  at  each  end 
of  a  sleeper.  The  platform  is  secured  in  its  place 
by  driving  stakes  around  the  edges. 

There  are  two  principal  platforms  for  the  siege-service, 
viz.,  the  grim-platform,  and  the  rawtor-platform.  The 
former  is  composed  of  twelve  sleepers  and  thirty-six 
deck-planks;  the  mortar-platform  of  six  sleepers  and 
eighteen  deck-planks. 

A  simple  and  strong  mortar-platform,  called  the  rail- 
platform  may  be  used  where  trees  or  timber  can  be 
easily  procured.  This  is  composed  of  three  sleepers 
and  two  rails,  secured  by  driving  stakes  at  the  angles 
and  at  the  rear  ends  of  the  rails.  The  rails  are  placed 
at  the  proper  distance  apart  to  support  the  cheeks  of 
the  bed. 


SEA-COAST   CAEEIAGES.  243 


SEA-COAST  CARRIAGES. 

211.  cia§sification.  Sea-coast  carriages  are  divided 
into  barbette,  casemate,  and  flank-defence  carriages,  de- 
pending upon  the  part  of  a  work  in  which  they  are 
mounted. 

212.  Material.  Heretofore,  nearly  all  sea-coast  car- 
riages were  made  of  wood ;  but  in  consequence  of  the 
great  difficulty  of  preserving  this  material  from  decay, 
especially  when  exposed  to  the  dampness  of  casemates, 
it  has  been  determined  to  replace  it  by  wrought-iron ; 
and  strong,  cheap,  and  manageable  carriages  have  been 
devised  and  tested  for  this  service. 

The  principal  feature  in  the  construction  of  the  new 
carriages,  is  a  peculiar  combination  of  boiler-plate  and 
rolled  beams,  which  gives,  with  requisite  lightness,  great 
strength  and  stiffness  to  the  important  parts. 

213.  Gun-carriage.  All  sea-coast  carriages  are  com- 
posed of  two  principal  parts,  viz.,  the  gun-carriage  (1), 
and  the  chassis  (2),  (fig.  66). 


\  Fig.  66. 

Gun-carriage.  The  purpose  of  the  gun-carriage  being 
to  support  the  piece,  it  should  be  so  constructed  that 
the  piece  can  be  elevated  or  depressed,  in  aiming ;  and 


244     ARTILLERY    CARRIAGES. SEA-COAST    CARRIAGES. 

run  into  and  out  of  battery,  in  firing.  The  term  "  in 
battery,"  as  applied  to  sea-coast  guns,  refers  to  the  posi- 
tion which  the  piece  occupies  when  it  is  ready  to  be* 
fired — in  casemate  pieces  the  muzzle  must  be  in  the 
throat  of  the  embrasure,  and  in  barbette-pieces,  directly 
Over  the  superior  slope  of  the  parapet. 

The  gun-carriage  is  composed  of  two  cheeks,  held  to- 
gether by  iron  straps,  called  transoms. 

Each  cheek  is  formed  of  a  piece  of  boiler-plate,  cut  to 
a  triangular  shape,  and  stiffened  by  ribs,  made  by  bolt- 
ing trough-beams  to  the  inner  sides  of  the  cheeks. 
Three  trough-beams  are  placed  on  each  cheek,  in  such 
positions  as  will  best  resist  the  strains  imposed  on  it. 
These  are  shown  by  the  broken  lines  of  the  figure.  The 
form  of  the  transom-straps  is  shown  at  (3) ;  the  ends, 
which  are  bent  at  right  angles  to  the  body  of  the  strap, 
are  pierced  with  holes  for  the  screw-bolts,  which  secure 
them  to  the  cheeks. 

Trunnion-plates  are  placed  on  the  top  of  the  cheeks, 
for  the  trunnions  to  rest  in  ;  and  the  bottom  of  each 
cheek  rests  upon  a  plate,  called  the  shoe.  The  move- 
ment of  the  carriage  to  and  from  battery,  is  regulated 
by  a  pair  of  eccentric  manosuv ring-wheels  (4),  which 
are  placed  underneath,  and  a  little  in  front  of  the  centre 
of  the  trunnions. 

When  it  becomes  necessary  to  check  the  recoil  of  the 
gun-carriage,  the  wheels  are  thrown  out  of  gear  by 
means  of  a  handspike,  and  the  forward  part  of  the  car- 
riage moves  on  sliding-friction ;  when  it  becomes  neces- 
sary to  move  it  to  battery,  the  wheels  are  thrown  into 
gear,  and  the  carriage  moves  on  rolling-friction. 

Elevating-screw.    The  elevating-screws  of  sea-coast 


SEA-COAST    CARRIAGES.  245 

carriages  are  of  two  kinds.  One  is  worked  by  a  geared 
nut,  which  is  made  to  revolve  by  a  bevelled  spur-wheel, 
attached  to  one  end  of  a  shaft  at  right  angles  to  the 
cheek.  The  other  end  of  the  shaft  projects  from  the 
right  side  of  the  carriage,  and  is  armed  with  a  handle 
having  four  branches  (5).  This  screw  is  used  for  low 
angles  of  elevation.  In  pieces  without  preponderance, 
a  simple  handspike  and  fulcrum  are  all  that  is  required 
to  elevate  and  depress  with  facility.  Elevating-screws 
are  supported  by  iron  trough-beams,  the  ends  of  which 
are  fastened  to  the  cheeks  by  screw-bolts. 

Elevating -arc.  The  elevating-arc  (8)  is  made  of  brass, 
and  attached  to  the  upper  edge  of  the  right  cheek  by  a 
joint,  which  allows  it  to  be  folded  down  when  not  in 
use.  It  is  graduated,  by  means  of  a  mark  on  the  base- 
ring,  and  is  employed  to  measure  the  elevation  of  the 
piece.  It  may  be  also  used  for  giving  direction  to  the 
piece  by  sighting  along  its  inner  surface  and  the  ex- 
tremity of  the  rimbase. 

Chassis.  The  chassis  is  the  movable  railway  along 
which  the  gun-carriage  moves  to  and  from  battery.  It 
is  composed  of  two  long  i  shaped  wrought-iron  rafo 
fastened  together  by  transom-straps,  as  in  the  gun- 
carriage.  To  retard  the  recoil  of  the  piece  when  fired, 
and  to  facilitate  its  motion  to  battery,  the  rails  are  in- 
clined from  the  front  to  the  rear,  at  an  angle  of  1  upon 
20. 

To  permit  the  chassis  to  be  moved  horizontally,  and 
thereby  to  give  the  proper  direction  to  the  piece  in 
aiming,  it  is  supported  on  traverse-wheels  (6,  6),  which 
roll  upon  circular  plates  of  iron,  fastened  to  the  floor  of 
the  battery,  called  traverse-circles. 


246     ARTILLERY    CARRIAGES. SEA-COAST    CARRIAGES. 

The  motion  of  the  gun-carriage  is  checked,  in  front 
and  rear,  by  pieces  of  iron,  riveted  to  the  top  of  the 
rails,  called  hurters  and  counter-liurters  (7,  7) ;  and  it  is 
prevented  from  slipping  off  sidewise,  by  pieces,  called 
guides,  bolted  to  the  inner  sides  of  the  cheeks. 

Pintle,  The  pintle  is  the  fixed  centre  around  which 
the  chassis  is  traversed.  It  is  formed  of  a  stout  piece 
of  iron,  strongly  secured  to  masonry,  if  the  battery  be  a 
fixed  one,  or  cross-pieces  of  timber  bolted  to  a  platform 
of  timber  which  is  imbedded  in  the  ground,  if  it  be  of  a 
temporary  nature.  In  casemate  batteries,  the  pintle  is 
placed  immediately  under  the  throat  of  the  embrasure, 
and  the  chassis  is  connected  with  it  by  a  stout  strap  of 
iron,  called  the  tongue.  The  muzzle  of  the  piece,  when 
in  battery,  is  situated  in  the  throat  of  the  embrasure — 
a  position  which,  taken  in  connection  with  that  of  the 
pintle,  gives  the  greatest  horizontal  field  of  fire. 

In  the  ordinary  barbette-carriage,  the  pintle  is  gener- 
ally placed  under  the  centre  of  the  front  transom  of  the 
chassis;  but  in  the  columbiad-carriage,  it  is  placed  un- 
der the  centre  of  the  middle  transom.  In  the  first  case 
tjje  horizontal  field  of  fire  is  limited  to  150°;  and  the 
front  traverse-wheels  are  dispensed  with.  In  the  co- 
lumbiad-carriage, the  piece  sweeps  the  entire  horizon, 
and  the  chassis  is  supported  at  a  point  where  it  is  sub- 
jected to  a  very  great  strain  when  the  piece  is  fired  as  a 
mortar. 

The  barbette-pintle  can  be  made  movable  by  attach- 
ing it  to  a  frame  running  upon  a  railway,  situated  along 
the  foot  of  the  parapet.  This  affords  the  means  of  con- 
centrating an  increased  number  of  pieces  upon  the  front 
of  attack,  or  of  protecting  them  from  an  enfilading  fire, 


SEA-COAST   CARRIAGES.  247 

by  removing  them  under  the  shelter  of  traverses.  This 
plan  is  employed  in  the  Austrian  service. 

Prop,  c&c.  Props  are  attached  to  the  rear  extremi- 
ties of  the  columbiad-barbette  chassis-rails,  to  prevent 
the  chassis  from  being  tipped  up  when  the  gun-carriage 
recoils  with  violence  against  the  counter-hurters ;  and 
hooks  are  placed  along  the  web  of  the  chassis-rail  for 
the  attachment  of  the  handspikes  when  they  are  not  in 
use. 

214.  Kinds.  The  different  sea-coast  carriages  are 

Barbette. 
One  for  15-inch  columbiad. 
"        10-inch  " 

"         8-inch 

"         8-inch  howitzer,  42-pdr.  and  32-pdr.  guns. 
"       24-pdr.  and  all  smaller  guns. 

Casemate. 
One  for  8-inch  columbiad  and  42-pdr.  gun. 
"       32-pdr.  gun  and  24-pdr.  gun. 
"       24-pdr.  howitzer — flank  defence. 

The  carriage  for  one  calibre  can  be  altered  to  fit  that 
of  another,  by  changing  the  trunnion-plates  and  transom- 
straps.  The  parts  of  all  the  carriages,  as  far  as  practica- 
ble, are  made  to  interchange  with  each  other.* 

*  By  a  late  arrangement,  the  8  and  1 0-in.  columbiads  can  be  mounted  on  front 
pintle  barbette-carriages,  and  the  10-in.  columbiad  is  mounted  in  casemate  batteries. 


^/  /^  ^<^^y 


248 


MACHINES   AND   IMPLEMENTS. 


CHAPTER  V. 


MACHINES  AND  IMPLEMENTS 


215.  Object.  Artillery  machines  are  employed  to 
mount  and  dismount  cannon  from  their  carriages,  and 
to  transport  artillery  material  from  one  part  of  a  work 
to  another.  They  comprise  the  gin,  the  ding-cart,  the 
casemate-truck,  the  hand-cart,  the  lifting-jack,  and  the 
lever-jack. 

216.  Gin.  A  gin  is  a  tripod  formed  of  ash  or  spruce 
poles.  Two  of  the  poles  are  joined  together  by  two 
cross-bars  of  wood  or  iron  (1,  2),  see  fig.  67,  and  are 
called  the  legs.  The  third  is  called 
the  pry -pole,  and  is  used  in  elevating 
the  gin  to  its  proper  position.  The 
hoisting  apparatus  is  supported  by  a 
clevis  which  is  secured  by  the  bolt 
which  unites  the  legs  and  pry-poles ; 
it  consists  of  two  sets  of  iron  blocks, 
through  which  is  rove  a  rope  called  Fig.  67. 

the  fall,  and  which  is  wound  around  the  windlass  (3). 
The  windlass  is  worked  by  two  handspikes  which  fit 
into  brass  sockets,  one  at  each  extremity  of  the  wind- 
lass ;  the  operation  of  the  handspikes  is  made  continuous 
by  the  action  of  the  pawl  of  the  socket  on  the  ratchet 
of  the  windlass.  The  piece  to  be  raised  is  attached  to 
the  hook  of  the  lower  block,  by  a  stout  rope  called  a 


SLING  CART.  249 

sling,  which  passes  around  the  knob  of  the  cascable 
and  a  piece  of  wood  projecting  from  the  muzzle. 

Kinds.  There  are  three  kinds  of  gins,  viz. :  the  gar- 
rison gin,  the  casemate  gin,  and  the  field  and  siege  gin. 
The  last  mainly  differs  from  the  others  in  the  smaller 
size  and  lesser  strength  of  its  parts ;  the  casemate  gin  is 
not  so  tall  as  the  garrison  gin,  on  account  of  the  low- 
ness  of  the  casemate  roofs  under  which  it  is  used ;  in  all 
other  respects  the  two  are  alike. 

217.  siing-cart.  A  sling-cart  is  composed  of  two 
wheels  of  large  diameter,  an  axle-tree,  a  tongue,  and  the 
hoisting  apparatus  /  and  is  intended  to  transport  cannon 
and  their  carriages.  There  are  two  kinds,  viz. :  the 
wooden  sling-cart  and  the  iron  sling-cart. 

The  wheels  of  the  wooden 
sling-cart  are  eight  feet  in 
diameter,  (figure  68.)  The 
hoisting-apparatus  is  a  screw 
(1),  which  passes  vertically 
through  the  wooden  axle- 
tree,  and  is  worked  by  a  nut 
Fig.  68.  with  long  handles  (2).     The 

lower  part  of  this  screw  is  terminated  with  two  hooks, 
to  which  are  fastened  the  chains  and  trunnion-rings  (3). 
The  breech  of  the  piece  is  sustained  by  the  cascable 
chain  (4).  A  piece  may  be  also  raised  by  surrounding 
it  with  a  chain,  fastening  the  chain  to  the  hooks  (5,  5), 
and  depressing  the  tongue,  which  acts  as  the  long  arm 
of  the  lever. 

Iron  sling-cart.  The  iron  sling-cart  is  smaller  than 
the  wooden  one,  and  is  employed  to  transport  cannon 
in  siege-trenches,  <fcc.  (figure  69.)     The  weight  is  at- 


250 


MACHINES    AND    IMPLEMENTS. 


Fig.  69. 


tached  by  a  chain  or  rope  to 
the  hook  (1),  and  is  raised  by- 
pressing  down  the  tongue  (2), 
which  is  made  of  wood.  When 
sling-carts  are  to  be  moved,  they 
are  attached  to  the  pintle  of  a  field 
or  siege  limber. 
218.  Casemate  truck.  The  casemate  truck  (see  fig.  70) 
is  composed  of  a  stout  frame  of  wood  mounted  on  three 
barbette  traverse- wheels,  and  is  employed  to  move  can- 
non and  carriages  through  posterns  and  along  casemate 
galleries. 

Two  of  the  wheels  are 
placed  at  a,  and  one  at  h  ; 
the  latter  turns  around  a  ver- 
tical axis,  when  the  direc- 
tion of  the  truck  is  changed 
by  the  handle  (c).  The  rings  shown  in  the  figure  are 
for  the  purpose  of  attaching  drag-ropes. 

219.  L.MMiig-jack.  The  lifting-jack  is  a  small  but 
powerful  screw,  worked  by  a  geared  nut. 
It  is  useful  when  the  space  for  manoeuv- 
ring is  small,  and  the  number  of  men  is 
limited.  If  the  weight  to  be  raised  is 
sufiiciently  high,  the  lifting  power  is  ap- 
plied at  the  top  (a),  fig.  71;  if  it  be  low, 


Fig.  70. 


Fig.  71. 

it  is  applied  at  the  foot  (5). 

220.  .Lever-jack.  The  lever-jack  is  another  but  less 
powerful  apparatus  for  lifting.  It  consists  of  a  lever 
of  wood  (a),  fig.  72,  resting  on  a  bolt  (c),  which  passes 
through  holes  in  two  uprights  (b).  The  height  of  the 
bolt  is  varied  by  passing  it  through  different  holes  in 


LOADING.  251 

the  uprights  (eight  in  num- 
ber), and  the  power  of  the 
lever  is  regulated  by  a  notch- 
ed piece  of  cast  iron  screwed 
to  the  under  side  of  the  lever 

221.  Trench  cart.  The  trench  cart  is  a  common  hand- 
cart, employed  principally  in  the  transportation  of  am- 
munition in  siege-trenches.  In  the  Crimea,  trained 
pack-mules  were  employed  in  transporting  ammunition 
and  other  supplies,  from  the  depots  to  all  parts  of  the 
trenches. 


IMPLEMENTS  AND  EQUIPMENTS. 

Artillery  implements  and  equipments  are  employed 
in  loading,  pointing,  and  firing  cannon,  and  in  the  ma- 
noeuvre of  artillery  carriages. 

222.  Loading.  The  implements  for  loading  cannon  are, 

1st.  The  rammer-head  (1)  (Jig.  73),  is  a  short  cylin- 
drical piece  of  beech 
or  other  tough  wood, 
F&  *3-  fixed  to  the  end  of  a 

long  stick  of  ash  (3),  called  a  staff,  and  is  employed  to 
push  the  charge  to  its  place  in  the  bore  or  chamber  of 
a  cannon. 

2d.  The  sponge  is  a  woollen  brush  (2),  attached  to  the 
end  of  a  staff,  for  the  purpose  of  cleaning  the  interior 
of  cannon,  and  extinguishing  any  burning  fragments 
of  the  cartridge  that  may  remain  after  firing. 

In  the  field  and  mountain  services,  the  rammer-head 
and  sponge  are  attached  to  the  opposite  ends  of  the 


252  MACHINES    AND   IMPLEMENTS. 

same  staff;  in  the  siege  and  sea-coast  services  they  are 
attached  to  separate  staves. 

To  protect  the  sponge  from  the  weather,  it  should, 
when  not  in  use,  be  enclosed  in  a  cover  made  of  canvas 
and  painted. 

3d.  The  ladle  is  a  copper  scoop  (1),  fig.  74,  attached 

to  the  end  of  a  staff 
for  the  purpose  of  with- 
drawing the  projectile 
Fig.  74  of  a  loaded  piece.     La- 

dles are  only  used  for  siege  and  sea-coast  cannon,  as 
field  and  mountain  cannon  can  be  unloaded  by  raising 
the  trail  of  the  carriage,  which  permits  the  projectile  to 
slip  out  by  its  own  weight. 

4th.  The  worm  (fig.  74),  is  a  species  of  double  cork- 
screw, (2),  attached  to  a  staff,  and  is  used  in  field  and 
siege  cannon  to  withdraw  a  cartridge. 

5th.  The  gunner's  haversack  is  made  of  leather,  and 
suspended  to  the  side  of  a  cannonier  by  a  shoulder-strap. 
It  is  used  to  carry  cartridges  from  the  ammunition-chest 
to  the  piece,  in  loading. 

6th.  The  pass-box  is  a  wooden  box  closed  with  a  lid, 
and  carried  by  a  handle  attached  to  one  end.  It  takes 
the  place  of  the  haversack  in  siege  and  sea-coast  service, 
where  the  cartridge  is  large. 

7th.  The  tube-pouch  is  a  small  leather  pouch  attached 
to  the  person  of  a  cannonier  by  a  waist-belt.  It  con- 
tains the  friction-tubes,  lanyard,  priming-wire,  thumb- 
stall,  &c. 

8th.  The  budge-barrel  is  an  oak  barrel  covered  with 
copper  hoops.  To  the  top  is  attached  a  leather  cover, 
which  is  gathered  with  a  string,  after  the  manner  of  the 


LOADING.  253 

mouth  of  a  bag.  It  is  employed  to  carry  cartridges 
from  the  magazine  to  the  battery,  in  siege  and  sea-coast 
services. 

9th.  The  priming-wire  is  used  to  prick  a  hole  in  a 
cartridge  for  the  passage  of  the  flame  from  the  vent.  It 
is  a  piece  of  wire,  pointed  at  one  end,  and  the  other  is 
formed  into  a  ring  which  serves  as  a  handle. 

10th.  The  thumbstall  is  a  buckskin  cushion,  attached 
to  the  finger  to  close  the  vent  in  sponging. 

11th.  The  fuze-setter  is  a  brass  drift  for  driving  a 
wooden  fuze  into  a  shell. 

12th.  The  fuze-mallet  is  made  of  hard  wood,  and  is 
used  in  connection  with  the  setter. 

13th.  The  fuze-saw  is  a  10-inch  tenon  saw  for  cutting 
wooden  or  paper  fuzes  to  a  proper  length. 

14th.  The  fuze-gimlet  is  a  common  gimlet,  which 
may  be  employed  in  place  of  the  saw  to  open  a  com- 
munication with  the  fuze  composition. 

15th.  The  fuze-auger  is  an  instrument  for  regulat- 
ing the  time  of  burning  of  a  fuze,  by  removing  a  cer- 
tain portion  of  the  composition  from  the  exterior.  For 
this  purpose  it  has  a  movable  graduated  scale,  which 
regulates  the  depth  to  which  the  augur  should  pene- 
trate. 

16th.  The  fuze-rasp  is  a  coarse  file  employed  in  fitting 
a  fuze-plug  to  a  shell. 

17th.  The  fuze-plug  reamer  is  used  to  enlarge  the 
cavity  of  a  fuze-plug,  after  it  has  been  driven  into  a  pro- 
jectile, to  enable  it  to  receive  a  paper  fuze. 

18th.  The  shell-plug  screw  is  a  wood  screw  with  a 
handle  ;  it  is  used  to  extract  a  plug  from  a  fuze-hole. 

19th.  The  fuze-extractor  is  worked  by  a  screw,  and 


254  MACHINES    AND    IMPLEMENTS. 

is  a  more  powerful  instrument  than  the  preceding ; 
it  is  used  for  extracting  wooden  fuzes  from  loaded 
shells. 

20th.  The  mortar-scraper  is  a  slender  piece  of  iron 
with  a  spoon  at  one  end,  and  a  scraper  at  the  other,  for 
cleaning  the  chamber  of  a  mortar. 

21st.  The  gunner*  s  sleeves  are  made  of  flannel  or 
serge,  and  are  intended  to  be  drawn  over  the  coat- 
sleeves  of  the  gunner,  and  prevent  them  from  being 
soiled  while  loading  a  mortar. 

22  d.  The  funnel  is  made  of  copper,  and  is  used  in 
pouring  the  bursting  charge  into  a  shell. 

23d.  The  powder-measures  are  made  of  copper,  of 
cylindrical  form,  and  of  various  sizes,  for  the  purpose  of 
determining  the  charges  of  shells  and  cannon,  by  meas- 
urement. 

24th.  The  lanyard  is  a  cord,  one  end  of  which  has  a 
small  iron  hook,  and  the  other  a  wooden  handle.  It  is 
used  to  explode  the  friction-tubes  with  which  cannon 
for  the  land  service  are  now  fired. 

25th.  The  gunner's  pincers,  gimlet,  and  ventpunch 
are  instruments  carried  in  the  tube-pouch  for  removing 
ordinary  obstructions  from  the  vent. 

26th.  The  shell-hooks  is  an  instrument  constructed  to 
fasten  into  the  ears  of  a  shell,  for  the  purpose  of  lifting 
it  to  the  muzzle  of  the  piece. 

223L  Pointing.  The  implements  for  pointing  are : 

1st.  The  gunner's  level  (fig.   75),  is  an 

instrument   for   determining    the    highest 

points  of  the  breech  and  muzzle  of  a  cannon 

when  the  carriage- wheels  stand  on  uneven 

Fig.  75.     '  ground.     It  is  made  of  a  brass  plate  (1),  the 


POINTING. 


255 


lower  edge  of  which  is  terminated  by  two  steel  points 
(2  2)  which  rest  upon  the  surface  of  the  piece.  A  spirit- 
level  (3)  is  attached  to  the  plate  with  its  axis  parallel  to 
the  line  joining  the  points  of  contact.  When  the  level 
is  in  position,  the  vertical  slide  (4)  is  pressed  down  with 
the  finger  to  mark  the  required  point. 

2d.  The  tangent-scale  (fig.  76)  is  a  brass  plate,  the 
lower  edge  of  which  is  cut  to  the  curve 
of  the  base-ring  of  the  piece,  and  the 
upper  edge  is  formed  into  offsets  which 
correspond  to  differences  of  elevation 
Fig.  "76  0f  a  quarter  of  a  degree.     It  is  used  in 

pointing,  by  placing  the  curved  edge  on  the  base-ring, 
with  the  radius  of  the  offset  corresponding  with  the 
highest  point  of  the  ring,  and  sighting  over  the  centre 
of  the  offset  and  the  highest  point  of  the  swell  of  the 
muzzle. . 

3d.  The  breech  sight  (fig.  77),  is  a  more  accurate  form 
of  the  tangent  scale.  It  consists  of  a  vertical 
scale  (1),  graduated  to  degrees  and  eighths 
of  degrees,  and  a  curved  base  (2),  which  rests 
upon  the  breech  of  the  gun.  A  slide  is  at- 
tached to  the  vertical  piece,  which  has  a  small 
hole  or  notch  cut  on  its  upper  edge,  through 
which  the  aim  is  taken.  The  slide  is  fixed  at 
any  point  by  a  thumbscrew. 
4th.  The  pendulum  Kausse  (jig.  78),  is  used  to  point 
field-pieces,  and  at  the  same  time  to  obviate  the  error 
which  arises  when  the  wheels  of  the  carriage  stand  on 
uneven  ground.  It  is  composed  of  a  scale  (1),  arranged 
as  a  pendulum,  a  suspension  piece  (2),  and  a  seat  which 
is  screwed  to  the  breech  of  the  gun.     A  slot  is  cut  in 


Fig.  77. 


256 


MACHINES    AND    IMPLEMENTS. 


Fig.  78. 


the  suspension  piece  into  which  the  scale  is 
inserted,  and  fastened  by  a  pivot,  which 
allows  it  to  vibrate  in  a  lateral  direction. 
The  scale  also  vibrates  in  a  longitudinal 
direction,  as  the  journals  of  the  suspension 
piece  are  free  to  turn  in  the  grooves  cut  in 
the  seat  to  receive  them,  thus  assuming  a 
vertical  position  independently  of  the  surface 
of  the  ground  on  which  the  carriage  stands. 
In  order  that  the  line  of  metal  which  passes  through  the 
centre  of  motion  of  the  pendulum  may  be  parallel  to  the 
axis  of  the  piece,  a  front  sight  (4)  is  screwed  into  the 
swell  of  the  muzzle,  the  height  of  which  is  equal  to  the 
dispart  of  the  piece. 

The  length  of  each  graduation  is  equal  to  the  distance 
between  the  front  and  rear  sights,  multiplied  by  the  tan- 
gent of  the  corresponding  angle.  This  rule  applies  in 
graduating  all  breech-sights. 

5th.  The  gunner's  quadrant  (fig.  79)  is 
a  wooden  instrument  for  measuring  the 
angles  of  elevation  and  depression  of  can- 
non, and  particularly  of  mortars.  The 
figure  explains  the  nature  of  the  instru- 
ment and  its  mode  of  application.  The 
plumb-line  and  bob  (1),  when  not  in  use,  are  carried  in 
a  hole  formed  in  the  end  of  the  long  branch,  and  cov- 
ered with  a  brass  plate. 

224.  Manoeuvre.  The  principal  manoeuvring  imple- 
ments are — 

1st.  The  trail  handspike  (fig.  80,  1),  which  is  made 
of  wood,  and  attached  to  the  trail  of  a  field-carriage  for 
the  purpose  of  giving  direction  to  the  piece  in  aiming. 


Fig.  79. 


MA1SXEUVRE. 


257 


Fig.  80. 


When  the  carriage  is 
limbered,  the  hand- 
spike is  attached  to 
the  cheek  by  means 
of  a  ring  and  hook. 
2d.  The  manoeuvring  handspike  (3)  (fig.  80)   is  also 
made  of  wood,  but  it  is  longer  and  stouter  than  the 
preceding ;  it  is  used  for  siege  and  sea-coast  carriages 
and  gins. 

3d.  The  shod  handspike  (2)  (fig.  80)  is  made  of 
wood,  armed  with  an  iron  point,  which  is  turned  up  in 
a  way  to  prevent  slipping  on  the  platform.  It  is  par- 
ticularly useful  in  the  service  of  mortars  and  sea-coast 
carriages. 

4th.    The    truck    hand- 
ike  (1)  (fig.  81)  is  made 
of  iron,  and  is  employed 
to  work  the  manoeuvring: 
Kg.  si.  wheels    of    sea-coast    car- 

riages, by  inserting  it  in  the  holes  formed  in  the  circum- 
ference of  the  wheels. 

5th.  The  eccentric  handspike  (2)  (jig.  81)  is  used  to 
throw  the  eccentric  axis  of  the  manoeuvring  wheels  of 
sea-coast  carriages  into  and  out  of  gear,  and  for  this 
purpose  it  has  a  head,  with  a  hexagonal  hole  which  fits 
upon  the  extremities  of  the  eccentric  axle-tree. 

6th.  The  roller  handspike  (3)  (fig.  81)  supplies  the 
place  of  rear  manoeuvring  wheels  in  certain  of  the  new 
sea-coast  gun-carriages.  It  is  operated  by  inserting  the 
point  of  the  handspike  under  the  heel  of  the  carriage- 
shoe,  and  pressing  down  the  long  arm  of  the  lever ;  in 

this  way  the  weight  of  the  rear  portion  of  the  carriage 
17 


258  MACHINES    AND    IMPLEMENTS. 

is  thrown  upon  the  roller  (£),  which  moves  upon  the 
rail  of  the  chassis. 

7th.  The  prolonge  is  a  stout  hemp  rope,  occasionally 
employed  in  field  service  to  connect  the  lunette  of  the 
carriage  and  pintle-hook  of  the  limber  when  the  piece 
is  fired.  It  is  terminated  at  one  end  with  a  hook,  at 
the  other  with  a  toggle,  and  has  two  intermediate  rings, 
into  which  the  hook  and  toggle  are  fastened  when 
it  is  necessary  to  shorten  the  distance  between  the  car- 
riages. 

8th.  The  sponge-bucket  is  made  of  sheet-iron,  and  is 
attached  to  field-carriages;  it  is  used  for  washing  the 
bore  of  the  piece. 

9th.  The  tar-bucket  is  also  made  of  sheet-iron,  and  is 
used  to  carry  the  grease  for  the  wheels. 

10th.  The  watering-bucket  is  made  of  sole-leather, 
riveted  at  the  seams,  and  is  used  to  water  horses.  Gut- 
ta  Percha  watering-buckets  are  sometimes  used. 

11th.  The  water-buckets  are  made  of  wood,  and  bound 
with  iron  hoops.  There  are  two  kinds,  one  for  the 
travelling-forge,  and  the  other  for  the  service  of  garrison- 
batteries. 

12th.  The  drag-rope  has  a  hook  at  one  end,  a  loop  at 
the  other,  and  six  wooden  handles  placed  about  four 
feet  apart.  It  is  used  whenever  it  may  be  necessary  to 
employ  a  number  of  men  in  hauling  loads,  or  extrica- 
ting a  carriage  from  a  difficult  part  of  a  road. 

13th.  The  men's-harness  is  similar  to  the  drag-rope, 
except  that  the  rope  is  stouter,  and  the  handles  are  re- 
placed by  leather  loops  which  pass  over  the  shoulders 
of  the  men,  to  enable  them  to  exert  their  strength  to 
advantage. 


CAREIAGES. 


259 


14th.  The  bill-hook,  or  hand- 
bill (fig.  82),  is  used  for  cutting 
twigs. 


Fig.  82. 


15th.  The  screw-jack  (fig.  83)  is  a  lifting 
machine,  composed  of  a  screw  worked  by  a 
movable  nut  (2),  supported  on  a  cast-iron 
stand  (3).  It  is  useful  in  greasing  carriage- 
wheels. 


PRESERVATION  AND  REPAIRS. 


Fig.  83. 


225.  Preservation.  Carriages,  implements,  Ac.,  are 
preserved  in  dry  and  airy  store-houses.  Each  kind 
should  be  piled  so  as  to  occupy  the  least  space,  and  each 
pile  should  be  marked  with  the  nature  and  number  of 
the  contents,  and  should  be  convenient  of  access.  Care 
should  be  taken  to  place  strips  of  board  under  the 
wheels  and  trails  of  carriages,  if  they  are  stowed  away 
on  a  ground  floor. 

226.  Repairs.  Carriages  are  repaired  in  the  field 
from  the  spare  parts  and  materials  carried  in  the  bat- 
tery-wagons. 


DESTRUCTION,  ETC.,  OF  MATERIAL. 

227.  carriages,  &c.  When  it  is  necessary  to  aban- 
don artillery  material,  it  must  be  destroyed,  to  prevent 
it  from  falling  into  the  hands  of  the  enemy.  Caissons 
should  be  blown  up,  or  water  poured  over  the  contents. 
Carriages  should  be  formed  into  a  pile,  and  burned ;  or, 
if  it  be  only  necessary  to  prevent  them  from  being  moved, 
the  spokes  of  the  wheels  and  poles  may  be  cut  off  with 


260 

an  axe  or  saw.     The  implements  should  be  taken  away 
or  destroyed. 

228.  Cannon.  Cannon  may  be  permanently  or  tem- 
porarily disabled.  The  first  is  done  by  bursting,  bend- 
ing the  chase,  breaking  off  the  trunnions,  and  scoring 
the  surface  of  the  bore. 

To  burst  an  iron  piece,  load  it  with  a  heavy  charge  of 
powder,  and  fill  the  bore  with  sand,  or  with  shot,  and 
fire  it  at  a  high  elevation.  To  bend  the  chase  of  a 
bronze  cannon,  fire  one  piece  against  another,  muzzle  to 
muzzle,  or  the  muzzle  of  one  to  the  chase  of  another,  or 
light  a  fire  under  the  chase  and  strike  on  it  with  a 
sledge-hammer.  To  break  off  a  trunnion  of  an  iron  can- 
non, strike  on  it  with  a  heavy  hammer,  or  fire  a  shotted 
gun  against  it.  To  score  the  surface  of  the  bore, 
cause  shells  to  burst  in  it,  or  fire  broken  shot  from  it 
with  high  charges. 

Cannon  are  temporarily  disabled  to  prevent  them 
from  being  immediately  used  by  the  enemy,  and  when 
they  are  expected  to  be  retaken.  This  operation  is  ac- 
complished by  means  of  a  spike. 

To  spike.  A  spike  is  made  of  hardened  steel,  with  a 
soft  point  that  it  may  be  clinched  on  the  inside  :  a  nail 
without  a  head,  or  a  bit  of  ramrod,  may  be  used  in 
place  of  a  regular  spike.  To  spike  a  piece,  drive  in  the 
spike  flush  with  the  outer  surface  of  the  vent,  and 
clinch  it  on  the  inside  with  a  rammer.  To  prevent 
the  spike  from  being  blown  out,  wedge  a  shot  in  the 
bottom  of  the  bore  by  wrapping  it  with  cloth  or  felt, 
or  by  means  of  iron  wedges,  driven  in  with  a  bar  of 
iron ;  wooden  wedges  might  be  easily  burned  out  by 
means  of  a  charcoal  fire  lighted  with  a  pair  of  bellows. 


TIMBER.  261 

When  a  piece  is  likely  to  be  retaken,  a  spring-spike 
is  used,  having  a  shoulder  to  prevent  its  being  too  easily 
extracted. 

To  unspihe.  To  nnspike  a  cannon,  attempt  to  drive 
the  spike  into  the  bore  with  a  punch ;  if  this  succeeds, 
and  the  bore  be  obstructed,  introduce  powder  into  the 
vent  to  force  the  obstacle  out.  If  it  do  not  succeed,  and 
the  spike  be  not  screwed  or  riveted  in,  and  the  bore  be 
not  obstructed,  put  in  a  charge  of  powder  equal  to  one- 
third  the  weight  of  the  shot,  and  ram  junk- wads  over  it 
with  a  handspike,  laying  on  the  bottom  of  the  bore  a 
strip  of  wood,  with  a  groove  on  the  under  side  for  a 
strand  of  quick-match,  by  which  fire  is  communicated  to 
the  charge ;  in  a  bronze  piece,  take  out  some  of  the 
metal  at  the  upper  orifice  of  the  vent,  and  pour  sulphuric 
acid  into  the  groove  before  firing.  If  this  method,  sev- 
eral times  repeated,  do  not  succeed,  unscrew  the  vent- 
piece,  if  it  be  a  bronze  cannon ;  or,  if  an  iron  one,  drill 
out  the  spike,  or  drill  a  new  vent. 

To  drive  out  a  shot.  To  drive  out  a  shot  wedged  in 
the  bore,  unscrew  the  vent-piece,  if  there  be  one,  and 
drive  in  wedges  so  as  to  start  the  shot  forward,  then 
ram  it  back  again  in  order  to  seize  the  wedges  with  a 
hook ;  or  pour  powder  in,  and  fire  it,  after  replacing  the 
vent-piece.  In  the  last  resort  bore  a  hole  in  the  bottom 
of  the  breech,  drive  out  the  shot,  and  stop  the  hole  with 
a  screw. 


MATERIALS  FOE  CARRIAGES,  &c. 
229.     Timber.     Timber  and   wrought  iron  are  the 


262  MATERIALS    FOR    CARRIAGES,    ETC. 

principal  materials  used  in  the  construction  of  artillery 
carriages  and  machines.     Of  the  former  are: 

White  oak.  The  bark  of  white  oak  is  white,  the  leaf 
long,  narrow,  and  deeply  indented ;  the  wood  is  of  a 
straw-color,  with  a  somewhat  reddish  tinge,  tough,  and 
pliable.  It  is  the  principal  timber  used  for  ordnance 
purposes,  being  employed  for  all  kinds  of  artillery-car' 
riages. 

Beech.  The  white  and  red  beeches  are  used  for  fuzes, 
mallets,  plane-stocks,  and  other  tools. 

Ash.  White  ash  is  straight-grained,  tough,  and  elas- 
tic, and  is  therefore  suitable  for  light  carriage-shafts  ;  in 
artillery,  it  is  chiefly  used  for  sponge  and  rammer  staves, 
sometimes  for  handspikes,  and  for  sabots  and  tool- 
handles. 

Elm.     Elm  is  used  for  felloes  and  for  small  naves. 

Hickory.  Hickory  is  very  tough  and  flexible;  the 
most  suitable  wood  for  handspikes,  tool-handles,  and 
wooden  axle-trees. 

Black  walnut.  Black  walnut  is  hard  and  fine-grained ; 
it  is  sometimes  used  for  naves,  and  the  sides  and  ends 
of  ammunition-chests ;  it  is  exclusively  used  for  stocks 
of  small  arms. 

Poplar.  White  poplar,  or  tulip- wood,  is  a  soft,  light, 
fine-grained  wood,  which  grows  to  a  great  size;  it  is 
used  for  sabots,  cartridge-blocks,  &c,  and  for  the  lining 
of  ammunition-chests. 

Pine.  White  pine  is  used  for  arm-chests  and  packing- 
boxes  generally,  and  for  building  purposes. 

Cypress.  Cypress  is  a  soft,  light,  straight-grained 
wood,  which  grows  to  a  very  large  size.  On  account 
of  the  difficulty  of  procuring  oak  of  a  suitable  kind  in 


(v  or  THE 
UNIVERSITY 

SELECTION    OF   TREES.  263 


the  Southern  States,  cypress  has  been  used  for  sea-coast 
and  garrison  carriages.  It  resists  better  than  oak  the 
alternate  action  of  the  heat  and  moisture  to  which  sea- 
coast  carriages  are  particularly  exposed  in  casemates; 
but  being  of  inferior  strength,  a  larger  scantling  of 
cypress  than  oak  is  required  for  the  same  purpose ;  and 
on  account  of  its  softness,  it  does  not  resist  sufficiently 
.the  friction  and  shocks  to  which  such  carriages  are 
liable. 

Basswood.  Basswood  is  very  light,  not  easily  split, 
and  is  an  excellent  material  for  sabots  and  cartridge- 
blocks. 

Dogwood.  Dogwood  is  hard  and  fine-grained,  suitable 
for  mal.ets,  drifts,  &c. 

230.  Selection  of  trees.  The  principal  circumstances 
which  affect  the  quality  of  growing  trees  are  soil,  cli- 
mate, and  aspect. 

Soil.  In  a  moist  soil,  timber  grows  to  a  larger  size, 
but  is  less  firm,  and  decays  sooner,  than  in  a  dry,  sandy 
soil ;  the  best  is  that  which  grows  in  a  dark  soil,  mixed 
with  stones  and  gravel;  this  remark  does  not  apply 
to  the  poplar,  willow,  cypress,  and  other  light  woods 
which  grow  best  in  wet  situations. 

Climate.  In  the  United  States,  the  climate  of  the 
Northern  and  Middle  States  is  most  favorable  to  the 
growth  of  timber  used  for  ordnance  purposes,  except 
the  cypress. 

Aspect.  Trees  growing  in  the  centre  of  a  forest,  or  on 
a  plain,  are  generally  straight er  and  freer  from  limbs 
than  those  growing  on  the  edge  of  the  forest,  in  open 
ground,  or  on  the  sides  of  hills,  but  the  former  are, 
at  the  same  time,  less   hard.      The  aspect  most  shel- 


264  MATERIALS    FOR    CARRIAGES,    ETC. 

tered  from  the  prevalent  winds  is  generally  most  favor- 
able to  the  growth  of  timber.  The  vicinity  of  salt 
water  is  favorable  to  the  strength  and  hardness  of  white 
oak. 

Selection.  The  selection  of  timber  trees  should  be 
made  before  the  fall  of  the  leaf.  A  healthy  tree  is 
indicated  by  the  top  branches  being  vigorous  and  well 
covered  w^ith  leaves ;  the  bark  is  clear  and  smooth,  and 
of  uniform  color.  If  the  top  has  a  regular,  rounded 
form;  if  the  bark  is  dull,  scabby,  and  covered  with 
white  and  red  spots,  caused  by  running  water  or  sap, 
the  tree  is  unsound.  The  decay  of  the  topmost  branch- 
es, and  the  separation  of  the  bark  from  the  wood,  are 
infallible  signs  of  the  decline  of  the  tree. 

231.  Felling.  The  most  suitable  season  for  felling 
timber  is  that  in  which  vegetation  is  at  rest,  whicli  is 
the  case  in  midwinter  and  midsummer.  Recent  experi- 
ments incline  to  give  preference  to  the  latter  season,  say 
the  month  of  July ;  but  the  usual  practice  is  to  fell  trees 
for  timber  between  the  first  of  December  and  the  middle 
of  March. 

The  tree  should  be  allowed  to  attain  full  maturity 
before  being  felled;  this  period,  in  oak  timber,  is  gen- 
erally at  the  age  of  seventy-five  to  one  hundred  years, 
or  upward,  according  to  circumstances.  The  age  of 
hard  wood  is  determined  by  the  number  of  rings  wrhich 
may  be  counted  in  a  section  of  a  tree. 

The  tree  should  be  cut  as  near  the  ground  as  possi- 
ble, the  lower  part  being  the  best  timber;  the  quality 
of  the  wood  is,  in  some  degree  indicated  by  the  color, 
which  should  be  nearly  uniform  in  the  heart- wood,  a 
little  deeper  toward    the    centre,  and  without  sudden 


SEASONING    AND    PRESERVING    TIMBER.  265 

transitions.     Felled  timber  should  be  immediately  strip- 
ped of  its  bark,  and  raised  from  the  ground. 

232.  Defect§  of  tree§.  Sap.  The  white  wood  next  to 
the  bark,  which  very  soon  rots,  should  never  be  used, 
except  that  of  hickory.  There  are  sometimes  found 
rings  of  light-colored  wood  surrounded  by  good  hard 
wood;  this  may  be  called  the  second  sap;  it  should 
cause  the  rejection  of  the  tree  in  which  it  occurs. 

Brashtoood.  This  is  a  defect  generally  consequent 
on  the  decline  of  the  tree  from  age ;  the  pores  of  the 
wood  are  open,  the  wood  is  reddish-colored,  it  breaks 
short,  without  splinters,  and  the  chips  crumble  to  pieces. 
This  wood  is  entirely  unfit  for  artillery  carriages. 

Dead-wood,  &c.  Wood  which  died  before  felling 
should,  generally,  be  rejected;  so  should  'knotty  trees, 
and  those  which  are  covered  with  tubercles  or  excres- 
cences. 

Cross-grained  wood.  Wood  in  which  the  grain  as- 
cends in  a  spiral  form,  is  unfit  for  use  in  large  scantlings  ; 
but  if  the  defect  is  not  very  decided,  the  wood  may  be 
used  for  naves  and  for  some  light  pieces. 

Splits,  &o.  Splits,  checks,  and  cracks,  extending  to- 
ward the  centre,  if  deep  and  strongly  marked,  make 
wood  unfit  for  use,  unless  it  is  intended  to  be  split. 
Wind-shakes  are  cracks  separating  the  concentric  layers 
of  wood  from  each  other;  if  the  shake  extends  through 
the  entire  circle,  it  is  a  serious  defect.  The  centre-heart 
is  also  to  be  rejected,  except  in  timber  of  very  large  size, 
which  cannot,  generally,  be  procured  free  from  it. 

233.  Seasoning  and  preserving  timber.  As  SOOn  as 
practicable,  after  the  tree  is  felled,  the  sapwood  should 
be  taken  off,  and  the  timber  reduced,  either  by  sawing 


266  MATERIALS    FOE    CARRIAGES,   ETC. 

or  splitting,  nearly  to  the  dimensions  required  for  use. 
Pieces  of  thickness,  or  of  peculiar  form,  such  as  those 
for  the  bodies  of  gun-carriages  and  for  chassis,  are  got 
out  with  a  saw;  smaller  pieces,  as  spokes,  are  split  with 
wedges.  Naves  should  be  cut  to  the  right  length,  and 
bored  out,  to  facilitate  seasoning  and  to  prevent  crack- 
ing. Timber  of  large  dimensions  is  improved  by  im- 
mersion in  water  for  some  weeks,  according  to  size,  after 
which  it  is  less  subject  to  warp  and  crack  in  seasoning. 

Seasoning.  To  season  or  dry  timber,  it  should  be 
piled  under  shelter,  in  such  manner  as  to  allow  a  free 
circulation,  but  not  a  strong  current  of  air,  around  each 
piece.  The  piles  should  be  taken  down  and  put  up 
again  at  intervals,  varying  with  the  length  of  time  the 
timber  has  been  cut. 

The  seasoning  of  timber  requires  from  two  to  eight 
years,  according  to  size.  Oak  timber  loses  about  one- 
fifth  of  its  weight  in  seasoning,  and  about  one-third  of 
its  weight  in  becoming  perfectly  dry. 

234.  Bill  of  timber.  Timber  for  the  ordnance  depart- 
ment is  purchased  in  pieces  of  the  size  required  to  make 
each  part.  A  list  of  the  pieces  for  a  certain  kind  of  car- 
riage, including  the  contents  of  each  piece,  in  board- 
measure,  is  called  a  bill  of  timber.  The  unit  of  board- 
measure  is  a  board  one  foot  square,  and  one  inch  thick. 

235.  Wrought  iron.  None  but  the  best  wrought  iron 
should  be  employed  in  ordnance  constructions.  Large 
and  peculiar-shaped  pieces,  as  axle-trees,  trunnion-plates, 
&c,  as  well  as  those  requiring  great  strength,  are  made 
from  hammered  shapes,  furnished  by  the  iron  manufac- 
turer, according  to  prescribed  patterns ;  other  parts  are 
made  of  rolled  iron.      Axle-trees  are  proved  by  sup- 


CONSTRUCTION.  267 

porting  them  at  the  arms,  and  dropping  a  heavy  weight 
upon  the  middle  of  the  body. 

236.  Construction.  Timber  for  gun-carriages  is  now, 
almost  entirely,  worked  into  shape  by  machinery;  the 
operations  are  sawing,  planing,  turning,  mortising  and 
tenoning,  dove-tailing,  <fcc. 

In  joining  together  the  different  pieces  of  a  carriage, 
regard  should  be  had  to  the  character  of  the  fibre  of  the 
wood,  and  the  effect  of  drying  in  changing  the  form  of 
the  piece.  If  a  piece  be  supported  at  both  ends,  as  in 
the  cases  of  carriage-stocks,  chassis-rails,  &c,  the  great- 
est convexity  of  the  fibre  should  be  placed  uppermost ; 
if  in  the  middle,  as  in  cases  of  hounds  of  limbers,  side- 
rails  of  caissons,  &c,  it  should  be  placed  downward. 

When  the  pieces  are  to  be  united  in  pairs,  as  cheeks, 
side-rails,  <fcc.,  use  such  pieces  as  have  nearly  the  same 
curvature  of  fibre. 

In  drying  a  piece  of  timber,  the  sap-wood  shrinks 
more  than  the  heart,  and  the  effect  will  be  to  warp  in 
the  direction  of  the  sap ;  therefore,  to  prevent  the  joint, 
formed  by  the  two  pieces  which  constitute  a  carriage- 
stock,  from  opening,  the  heart-wood  should  be  placed 
on  the  outside.  To  prevent  the  cheeks  frorr  warping 
inward,  place  the  heart-wood  on  the  inside.  In  hounds 
and  side-rails,  the  heart  side  should  be  placed  on  the 
outside,  as  this  will  have  a  tendency  to  tighten  the 
joints. 

When  pieces  are  to  be  joined,  the  surfaces  of  contact 
and  the  dowels  should  be  covered  with  a  good  coat  of 
white-lead.  Bolts  and  bolt-holes  should  be  well  covered 
with  tallow  moistened  with  neat's-foot  oil. 

The  surface  of  holes  for  elevating  screws  and  pintles 


2(38  MATERIALS  '  FOR    CARRIAGES,    ETC. 

should  be  painted.  If  woodwork  is  to  be  painted  im- 
mediately, it  should  have  a  priming  coat  of  lead  before 
the  irons  are  put  on ;  if  not,  it  should  receive  a  good 
coat  of  linseed  oil. 

237.  Painting.  For  service,  the  wood- work  of  car- 
riages and  machines  is  painted,  in  addition  to  the  pri- 
ming of  lead-color,  with  two  coats  of  olive  paint ;  the 
iron-work,  with  one  coat  of  lead,  and  one  coat  black 
paint.  Great  care  should  be  observed  to  protect  iron 
fortress-carriages  against  the  corroding  influence  of  the 
sea-coast  atmosphere ;  the  best  means  remains  to  be  de- 
termined by  experience;  at  present  they  are  covered 
with  one  coat  of  hot  linseed  oil  and  three  coats  of  a  red- 
dish brown  paint. 

238.  Wlodeii,  &c.  The  models,  <fec,  of  all  ordnance 
"materiel"  are  determined  by  the  ordnance  board, 
subject  to  the  revision  of  the  chief  of  ordnance,  and 
the  final  approval  of  the  secretary  of  war.  When  a 
model  has  been  duly  approved,  copies,  or  drawings  of 
it,  are  sent  to  the  different  arsenals  of  construction,  and 
from  these,  patterns  and  gauges  are  made  for  the  guid- 
ance of  the  workmen.  Patterns  are  generally  made  of 
well-seasoned  mahogany,  and  bound  with  strips  of 
brass;  gauges  are  made  of  sheet  iron  or  steel.  To  se- 
cure uniformity  of  work  at  the  different  arsenals,  it  is 
made  a  part  of  the  duty  of  the  inspector  of  arsenals  to 
see  that  the  patterns  correspond  with  the  originals ;  and 
it  is  always  the  duty  of  the  officers  stationed  at  an  arse- 
nal, to  see  that  the  work,  as  it  progresses,  corresponds 
with  the  patterns,  and  that  none  but  suitable  materials 
are  used. 

All  arsenals  may  be  divided  into  two  classes,  viz.,  ar- 


MODELS.  269 

serials    of    deposit    and    construction,    and    arsenals    of 

deposit  and  repairs.     The  arsenals  of  construction  are 

at  West  Troy,  N.  Y. ;  Watertown,  Mass. ;  Washington, 

D.   C. ;  Pittsburgh,  Pa.;   Fort  Monroe,  Va. ;   and  Fay- 

etteville,  N.  C. 

/ 


/r- 


./< 


270  SMALL- ARMS. 


CHAPTER  VI. 
SMALL-ARMS. 

239.  History,  Ancient  arms  consisted  of  three  kinds: 
1st.  Hand-arms,  for  close  conflict. 

2d.  Projectile  arms,  to  attain  an  enemy  at  a  distance. 
3d.  Defensive  arms,  to  protect  the  body. 

240.  Hand-arms.  Hand-arms  comprised  the  war -club, 
battle-axe,  pike,  sword,  and  sabre. 

lstr  The  war -club  was  a  stout  stick,  the  large  end  of 
which  was  armed  with  blades,  or  points  of  metal ;  that 
used  by  foot-soldiers  was  from  7  to  8  feet  long,  and 
weighed  from  20  to  30  pounds.  It  was  extensively 
used  in  the  middle  ages,  and  is  still  employed  by  cer- 
tain oriental  cavalry. 

2d.  The  battle-axe  was  at  first  made  of  stone  or  bone, 
and  afterward  of  metal.  This  weapon  was  much  used 
by  the  Celts  and  Gauls,  but  principally  by  the  Franks, 
who  hurled  it  with  great  skill  and  effect  against  an 
enemy. 

3d.  The  pike  was  generally  employed  both  by  infan- 
try and  cavalry.  That  for  the  infantry  was  very  long, 
as  in  the  case  of  the  Macedonian  lance,  or  sarissa,  the 
length  of  which  was  about  20  feet.  In  some  countries 
this  weapon  continued  to  be  used  as  late  as  the  seven- 
teenth century.  The  cavalry  lance  was  shorter  and 
lighter  than  the  preceding ;  it  is  still  used  by  certain 
kinds  of  cavalry. 


PEOJECTILE  AEMS.  27l 

The  Roman  javelin  was  a  short  pike,  about  6 -J-  feet 
long,  which  was  thrown  against  the  enemy.  The  spon- 
toon,  or  half -pike,  was  carried  by  French  infantry  officers 
as  late  as  the  time  of  Louis  XV.  The  halberd  and  the 
musket  with  its  bayonet  fixed,  are  pikes. 

4th.  Swords  and  sabres  have  usually  varied  in  charac- 
ter with  the  manner  of  fighting  of  different  nations ;  for 
instance,  the  Gauls  and  Germans,  who  defended  them- 
selves with  shields  made  of  willow,  or  other  light  wood, 
made  use  of  long  and  flexible  swords,  while  the  Greeks 
and  Romans,  who  wore  breastplates  and  helmets  of 
metal,  used  short  and  stout  swords. 

The  knights  of  the  middle  ages  carried  long  and 
heavy  swords,  which  they  wielded  with  both  hands. 

241.  Projectile  arms.  The  principal  projectile  arms, 
before  the  invention  of  gunpowder,  were  the  sling,  bow, 
and  crossbow. 

1st.  The  sling  was  formed  of  a  leather  cap  suspended 
by  two  cords ;  a  stone  was  placed  in  the  cap,  a  rapid 
rotary  motion  was  communicated  by  the  hand,  one  of 
the  cords  was  set  free,  and  the  stone  escaped  in  a  tan- 
gential direction,  and  was  thrown  to  a  distance  varying 
from  200  to  300  steps.  , 

•  2d.  The  bow  was  formed  of  a  piece  of  highly  elastic 
wood,  confined  in  a  bent  position  by  a  strong  cord  at- 
tached to  its  extremities ;  it  possessed  the  power  of  pro- 
jecting arrows  to  long  distances.  This  weapon  played 
a  very  important  part  in  ancient  warfare,  and  continued 
to  be  used  by  civilized  nations  to  a  comparatively  late 
period. 

In  the  middle  ages,  it  was  said,  that  a  skilful  archer 
could  fire  twelve  arrows  in  a  minute,  and  strike  a  man 


272  SMALL-ARMS. 

at  a  distance  of  100  yards.  If  certain  English  authors 
are  to  be  believed,  an  archer  who  could  not  perform 
this  feat,  was  disgraced.  According  to  their  statements, 
an  arrow  had  sufficient  force  to  penetrate  an  oak  plank, 
two  inches  thick,  at  the  distance  of  200  yards. 

3d.  The  crossbow  was  a  bow  attached  to  a  stock  hav- 
ing a  channel  to  guide  the  arrow.  It  is  said  to  have 
been  introduced  into  Europe  from  Asia,  during  the 
Crusades,  by  Richard  Cceur  de  Lion,  who  armed  the 
English  troops  with  it. 

At  present,  the  use  of  the  bow  is  confined  to  barba- 
rous tribes  alone;  the  skill  and  dexterity  with  which 
it  is  managed  by  the  prairie  Indians  of  this  country, 
make  it  an  exceedingly  formidable  weapon  at  short 
distances.* 

242.  Defensive  weapons.  Armor,  which  was  employed 
to  protect  the  most  exposed  part  of  the  body,  naturally 
followed  the  introduction  of  offensive  arms.  At  first  it 
was  made  of  plates  of  wood,  the  skins  of  certain  ani- 
mals, the  scales  of  serpents,  shells  of  turtles,  <fcc.,  and 
subsequently  of  metallic  plates,  or  of  cloth  folded  in  lay- 
ers. The  body  was  also  protected  in  rear  by  movable 
obstacles,  as  shields,  bucklers,  &c. 

Among  the  Romans  and  Greeks,  the  infantry  of  the 
line  wore  the  helmet,  the  breastplate,  a  species  of  half- 
boot  protected  with  iron,  and  the  buckler ;  the  cavalry, 
ordinarily,  wore  a  cuirass  formed  of  bands  of  leather, 
covered  with  plates  of  bronze. 

In  the  time  of  Charlemagne,  coats  of  mail,  formed  of 
small  chains,  were  much  worn.     These  were  followed 

*  Certain  Circassian  officers  ot  the  Russian  army  carry  bows  and  arrows  to  en- 
able them  in  a  surprise  to  kill  the  enemy's  sentinels  without  alarming  the  camp. 


ARQUEBUSE.  273 

by  complete  suits  of  metallic  armor,  which  were  worn 
until  the  introduction  of  fire-arms. 

243.  Portable  flre-arm§.  Portable  fire-arms  were  in- 
vented about  the  middle  of  the  fourteenth  century.  At; 
first  they  consisted  simply  of  a  tube  of  iron  or  copper, 
fired  from  a  stand  or  support.  They  were  loaded  with 
leaden  balls,  and  were  touched  off  by  a  lighted  match 
held  in  the  hand.  They  weighed  from  25  to  75  pounds, 
and  consequently  two  men  were  required  to  serve  them. 
The  difficulty  of  loading  these  weapons,  and  the  uncer- 
tainty of  their  effects,  as  regards  range  and  accuracy, 
prevented  them  from  coming  rapidly  into  use,  and  the 
crossbow  was  for  a  long  time  retained  as  the  principal 
projectile  weapon  for  infantry. 

Breech-loading  small-arms,  similar  in  principle  to  the 
cannon  described  in  section  66,  were  introduced  about 
the  same  time,  but  they  were  soon  thrown  aside  for 
want  of  strength  and  solidity. 

244.  Arquebuse.  The  difficulty  of  aiming  hand-can- 
non, arising  from  their  great  weight,  was  in  a  measure 
overcome  by  making  them  shorter,  and  supporting  them 
on  a  tripod,  by  means  of  trunnions  which  rested  in 
forks.  The  breech  was  terminated  with  a  handle 
which  was  held  in  the  right  hand,  while  the  match  was 
applied  with  the  left.  Thus  improved,  this  fire-arm 
was  called  the  arquebuse ;  it  was  employed  in  sieges, 
and  to  defend  important  positions  on  the  field  of  battle. 

The  next  improvement  in  the  arquebuse,  was  to  make 
it  lighter,  and  enclose  it  in  a  piece  of  wood,  called  the: 
stock,  the  butt  of  which  was  pressed  against  the  left 
shoulder,  while  the  right  hand  applied  the  match  to 
the  vent.     It  was  still  very  heavy,  and  in  aiming,  the, 

18 


274  SMALL-AKMS. 

muzzle  rested  in  the  crotch  of  a  fork  placed  in  the 
ground. 

245.  Matchlock.  To  give  steadiness  to  the  aim  while 
applying  the  match  to  the  priming,  a  species  of  lock 
was  next  devised,  which  consisted  of  a  lever  holding  at 
its  extremity  a  lighted  match.  In  firing,  the  lever  was 
pressed  down  with  the  finger  until  the  lighted  end  of 
the  match  touched  the  priming.  This  apparatus,  known 
as  the  serpentine,  continued  in  use  until  it  was  replaced 
by  the  wheel-lock,  which  was  invented  in  Nuremburg,  in 
1517. 

The  wheel-lock  consisted  of  a  grooved  wheel  of  steel, 
which  acted  through  a  half-revolution  on  a  piece  of 
alloy  of  iron  and  antimony,  placed  near  a  priming- 
charge  of  powder.  The  sparks  thus  evolved  fell  upon 
and  ignited  the  priming-charge. 

246.  Pistol.  The  first  pistol  was  a  wheel-lock  arque- 
buse,  so  small  that  it  could  be  held  and  fired  from  the 
extended  hand.  It  was  invented  in  1545,  in  Pistoia,  a 
city  of  Tuscany ;  hence  its  name. 

247.  Pctronei.  The  petronel  was  a  wheel-lock  arque- 
buse  of  larger  calibre  and  lighter  weight  than  its  pre- 
decessors. To  diminish  the  effect  of  the  recoil,  the  butt 
of  the  stock  was  much  curved,  and  had  a  broad  base, 
which  was  pressed  against  the  breastplate  of  the 
cuirass  when  the  piece  was  fired.  Two  sizes  of  the 
petronel  were  used,  one  for  infantry  and  one  for  cavalry. 

248.  Musket.  The  musket  was  first  introduced  by 
the  Spaniards,  under  Charles  V.  The  original  calibre 
of  the  musket  was  such  that  eight  round  bullets 
weighed  a  pound ;  the  piece  was,  consequently,  so 
heavy  that  it  was  necessary  to  fire  it  from  a  forked 


RIFLES.  275 

stick  inserted  in  the  ground.  The  size  of  the  bore  was 
finally  reduced  to  eighteen  bullets  to  the  pound ;  and 
from  this  arm  was  derived  the  late  smooth-bored 
musket. 

249.  Rifle§.  It  is  generally  stated  that  the  rifle  was 
invented  by  Gaspard  Zoller,  of  Vienna,  and  that  it  first 
made  its  appearance  at  a  target  practice  at  Leipsic,  in 
1498.  The  first  rifle  grooves  were  made  parallel  to  the 
axis  of  the  bore,  for  the  purpose  of  diminishing  the  fric- 
tion of  loading  forced  or  tightly-fitting  bullets.  It  was 
accidentally  discovered,  however,  that  spiral  grooves 
gave  greater  accuracy  to  the  flight  of  the  projectile,  but 
the  science  of  the  day  was  unable  to  assign  a  reason  for 
this  superiority,  and  the  form,  number,  and  twist  of  the 
grooves,  depended  on  the  caprice  of  individual  gun- 
makers. 

About  1600,  the  rifle  began  to  be  used  as  a  military 
weapon  for  firing  spherical  bullets.  In  1729,  it  was 
found  that  good  results  could  be  attained  by  using  ob- 
long projectiles  of  elliptical  form.  The  great  difficulty, 
however,  of  loading  the  rifle,  which  was  ordinarily  ac- 
complished by  the  blows  of  a  mallet  on  a  stout  iron 
ramrod,  prevented  it  from  being  generally  used  in. regu- 
lar warfare.  The  improvements  which  have  been  made 
in  the  last  thirty  years,  principally  by  officers  of  the 
French  army,  have  entirely  overcome  this  difficulty,  and 
rifles  are  now  almost  universally  used  in  place  of  smooth- 
bored  arms. 

The  rifle  has  ever  been  a  favorite  weapon  in  this 
country,  arising,  doubtless,  from  the  peculiar  circum- 
stances which  surrounded  its  early  settlers  and  pioneers, 
and  on  more  than  one  occasion  has  it  proved,  in  the 


276  SMALL-AKMS. 

hands  of  irregular  troops,  a  formidable  weapon  to  its 
enemies.  Until  1855,  the  mass  of  the  American  infan- 
try was  armed  with  smooth-bored  muskets,  but  since 
that  time  it  has  been  wholly  armed  with  rifles. 

250.  Bayonet.  In  spite  of  the  advantages  which  fire- 
arms possessed,  they,  like  the  arms  which  preceded 
them,  were  not  suited  to  resist  the  charge  of  cavalry. 
The  bayonet,  and  firing  in  closed  ranks,  were  unknown ; 
the  most  skilful  captains  of  the  age,  however,  sought  to 
combine  fire-arms  with  pikes,  in  such  a  manner  that  one 
might  afford  protection  to  the  other.  The  French  army 
was  thus  arranged  in  six  ranks,  four  with  muskets  and 
two  with  pikes;  on  the  introduction  of  the  bayonet,  it 
was  reduced  to  four,  and  finally  to  three  ranks. 

The  bayonet  derived  its  name  from  Bayonne,  where 
it  was  first  made,  in  1640.  At  first  it  was  formed  of  a 
steel  blade  attached  to  a  handle  of  wood,  which  was  in- 
serted into  the  bore  of  the  barrel,  except  in  the  opera- 
tions of  loading  and  firing.  Thirty  years  afterward  the 
wooden  handle  was  replaced  by  a  hollow  socket,  which 
fitted  over  the  muzzle  of  the  barrel ;  this  change  render- 
ed the  musket  at  all  times  a  pike  as  well  as  a  fire-arm, 
and  led  to  the  formation  of  modern  infantry. 

£51.  Flint-lock.  The  flint-lock  was  derived  from  the 
wheel-lock,  by  substituting  flint  for  the  alloy  of  iron 
and  antimony,  and  a  steel  battery  for  the  wheel.  It  was 
generally  introduced  into  the  French  army  in  1680,  and 
continued  to  be  used  in  all  military  services,  until  about 
1842,  when  it  gave  way  to  the  percussion-lock. 

252.  Loading.  In  proportion  as  fire-arms  were  im- 
proved, rapidity  of  fire  increased.  In  1703,  the  loading 
of  the  musket  was  performed  in  twenty-six  times,  and 


THRUSTING- ARMS.  277 

the  fire  of  infantry  was  necessarily  slow.  In  1744, 
the  employment  of  fine  powder  for  priming  was  dis- 
pensed with,  and  the  cartridge  (said  to  have  been  the 
invention  of  Gustavus  Adolphus)  was  adopted  in  its 
place. 

HAND-AKMS. 

253.  cia§§iflcation.  Hand-arms  are  divided  into  three 
classes,  depending  on  their  mode  of  operation. 

1st.   Tkrusting-arms,  which  act  by  the  pojnt. 
2d.    Cutting-arms,  which  act  by  the  edge. 
3d..  Thrusting  and  Cutting  arms,  which  act  either 
way. 

254.  General  principles.  The  object  of  all  hand- 
weapons  is  to  penetrate,  directly,  the  person  of  an  enemy. 
They  may  be  divided  into  three  distinct  parts,  viz. :  1st. 
The  point,  or  edge,  which  attains  the  object;  2d.  The 
body,  or  blade,  which  constitutes  the  mass  of  the  weap- 
on, and  transmits  the  force  of  the  hand  to  the  object; 
and,  3d.  The  handle,  or  point  of  application  of  the 
motive  force. 

The  mechanical  principles  to  which  they  may  be  re- 
ferred, are  the  lever  and  wedge. 

255.  Thru§tiiig-arms.  With  a  given  force  of  the  hand, 
acting  against  a  given  object,  the  penetration  of  a  thrust- 
ing-weapon  depends  upon  the  power  of  the  wedge 
formed  at  its  point.  The  effect  will  be  modified,  how- 
ever, by  the  position  of  the  axis  of  the  wedge,  for  if  it 
do  not  coincide  with  the  direction  of  the  impelling 
force,  there  will  be  a  component  force  which  acts  to 
turn  the  point  to  one  side. 


278  SMALL- ARMS. 

The  blade  of  a  thrusting- weapon  should,  therefore, 
be  straight,  and  should  taper  to  a  point.  To  guide  it 
easily,  the  centre  of  gravity  should  be  found  in  or  near 
the  handle ;  this  may  be  accomplished  by  grooving  the 
blade,  by  making  the  handle  heavy,  or  by  adding  a 
counterpoise  to  it. 

Kinds.  The  principal  thrusting-weapons  are  the 
straight  sword,  lance,  and  bayonet. 

The  straight  sword,  as  well  as  other  swords,  are  com- 
posed of  the  blade,  the  hilt,  and  the  guard. 


The  blade  (see  fig.  84)  is  divided  into  the  point  (d), 
the  middle  (c),  the  reinforce  (b),  the  shoulder  (a),  the 
tang,  or  portion  which  is  inserted  into  the  handle,  and 
the  grooves,  the  number  of  which  is  equal  to  the  num- 
ber of  faces,  or,  from  two  to  four. 

The  length  of  the  blade  varies  from  30  to  33  inches, 
the  width  is  from  \  to  \  of  an  inch,  and  the  weight  1 
to  H  pound. 

The  hilt  is  divided  into  the  knob  (i),  and  the  gripe 
(<7);  the  gripe  is  generally  made  of  wood,  covered 
with  leather  or  sheet  brass,  and  wrapped  with  wire  to 
give  it  roughness,  and  prevent  it  from  slipping  in  the 
hand. 

The  guard  is  composed  of  the  curved  branch  and 
cross-piece  (/),  and  the  plate  (e),  all  joined  in  one  piece. 
The  object  of  the  guard  is  to  protect  the  hand,  the  plate 


THRUSTING-ARMS.  279 

to  ward  off  the  point,  and  the  branch,  the  edge  of  the 
enemy's  sword. 

The  wounds  made  by  thrusting-swords,  particularly 
those  with  three  or  four  concave  sides,  are  very  danger- 
ous, as  they  close  up  externally  and  suppurate  inter- 
nally. 

In  experienced  hands  the  straight  sword  is  well 
adapted  to  encounter  one  of  its  kind,  but  it  is  too  weak 
to  parry  the  blows  of  a  sabre.  It  is  now  but  little 
used  in  this  country,  except  for  ornamental  purposes; 
the  sabre  being  preferred  as  a  service  weapon,  even  for 
infantry  officers. 


Fig.  85. 

The  lance.  The  lance,  or  pike,  is  composed  of  a  sharp 
steel  blade,  fixed  to  the  end  of  a  long  and  slender  han- 
dle of  wood.     (Fig.  85). 

The  blade  is  generally  from  8  to  10  inches  long,  and, 
in  order  that  it  may  combine  stiffness  with  lightness,  is 
grooved  after  the  manner  of  the  common  bayonet,  leav- 
ing three  or  four  ridges.  The  base  of  the  blade  has  a 
socket,  and  two  iron  straps,  for  securing  it  to  the  han- 
dle. Three  small  staples  are  sometimes  fastened  to  the 
handle,  below  the  blade,  for  the  purpose  of  attaching  a 
pemwn,  which  serves  as  an  ornament,  and  to  frighten 
the  enemy's  horses. 

The  handle  is  made  of  strong,  light,  well-seasoned 
wood.  The  lower  end  is  protected  with  a  tip  of  iron, 
and  a  leather  loop  (c)  is  attached  opposite  the  centre 
of  gravity,  to  enable  the  arm  to  carry  and  guide  the 


280  SMALL-ARMS. 

lance.     The  total  length  of  a  lance  varies  from  8^  to  11 
feet,  and  the  weight  is  about  4|  lbs. 

Mode  of  carrying.  On  horseback,  and  when  not  in 
use,  the  lance  may  be  carried  in  two  ways :  1st.  By 
placing  the  lower  end  in  a  leather  boot  attached  to  the 
stirrup,  and  passing  the  right  arm  through  the  leather 
loop ;  2d.  By  placing  the  lower  end  in  the  boot,  and 
strapping  the  handle  to  the  pommel  of  the  saddle.  The 
first  mode  enables  the  horseman  to  take  his  lance  with 
him  when  he  dismounts,  and  is  well  suited  to  light 
lances.     The  second  mode  is  necessary  for  heavy  lances. 

Advantages,  &c.  In  the  first  shock  of  a  cavalry 
charge,  and  in  the  pursuit  of  a  flying  enemy,  the  lance 
is  a  superior  weapon  to  the  sabre,  as  it  has  a  greater 
penetration,  and  attains  its  object  at  a  greater  distance ; 
but  in  the  hand-to-hand  conflict  which  follows  a  charge, 
the  latter  is  superior  to  the  former.  Hence,  it  has  been 
customary  in  certain  services  to  arm  a  portion  of  both 
light  and  heavy  cavalry  with  the  lance.  In  the  Rus- 
sian service,  the  front  rank  of  the  cuirassiers,  a  species 
of  heavy  cavalry,  is  armed  with  the  lance,  and  the  rear 
rank  with  the  long,  straight,  two-edged  sabre ;  and  in 
nearly  every  European  service,  the  lancers  constitute  an 
important  part  of  the  cavalry  organization.  It  is  also 
a  favorite  weapon  with  the  mounted  Indians  of  this 
country. 

Bayonet.  The  bayonet  is  a  pointed  blade  attached 
to  the  end  of  a  fire-arm,  to  convert  it  into  a  pike.  The 
mode  of  attachment  should  be  such  that  the  bayonet 
will  not  interfere  with  the  loading,  aiming,  and  firing 
of  the  piece ;  and  it  should  be  so  secure  as  not  to  be 
disengaged  in  conflict. 


THRUSTING- ARMS.  281 

The   musket-bayonet    is    com- 
I  posed  of  a  blade  (a),  (fig.  86), 
Fig.  86.  a  socket  (b),  and  a  clasp  (c). 

The  Sfefe  of  this  bayonet  is  made  of  steel,  18  inches 
long,  and,  to  give  it  lightness  and  stiffness,  its  three 
faces  are  grooved  in  the  direction  of  the  length.  The 
grooves  are  technically  called  flutes.  (See  cross-section 
of  blade.)  The  blade  is  joined  to  the  socket  by  the 
neck,  which  should  be  strong,  and  free  from  defects  of 
workmanship. 

The  socket  is  made  of  wrought  iron,  carefully  bored 
out  to  fit  the  barrel  of  the  piece  easily,  and  at  the 
same  time  closely.  It  is  secured  by  a  stud  (brazed  on 
the  barrel),  which  fits  into  a  crooked  channel,  or  groove, 
cut  in  the  socket,  and  by  a  movable  ring  called  the 
clasp. 

The  Sword-bayonet.  Short  arms,  such  as  carbines 
and  musketoons,  are  sometimes  furnished  with  bayo- 
nets of  sufficient  length  to  enable  these  arms  to  resist  a 
charge  of  infantry  or  cavalry. 

Such  bayonets  are   gen- 


erally made  in  the  form  of 
a  sword.  (Fig.  87.)  The 
back  of  the  handle  has  a 
groove  which  fits  upon  a  stud  on  the  barrel,  and  the 
cross-piece  of  the  handle  is  perforated  so  as  to  encircle 
the  muzzle  end  of  the  barrel.  The  bayonet  is  prevented 
from  slipping  off  by  a  spring  catch. 

The  handle  is  made  of  a  solid  piece  of  brass,  with  a 
hole  running  through  it  for  the  tang  of  the  blade,  which 
is  secured  by  riveting  down  the  point.  The  back  of 
the  blade  is  turned  toward  the  barrel,  and  the  body  is 


282  SMALL-ARMS. 

bent  outward,  that  neither  may  interfere  with  the  hand 
in  loading.  Its  length  is  about  23  inches,  and  its  breadth 
1^  inches.  The  sword  bayonet  is  too  heavy  to  be  car- 
ried habitually  fixed  to  the  barrel ;  ordinarily  it  is  carried 
as  a  side-arm,  for  which  purpose  it  is  well  adapted,  as 
it  has  a  curved  cutting  edge,  as  well  as  a  sharp  point. 
The  ordinary  bayonet,  when  not  fixed,  may  be  used  as  a 
poignard,  for  the  personal  defence  of  the  soldier. 

The  bayonet  contributes  very  much  to  the  efficiency 
of  a  military  fire-arm,  particularly  as  it  enables  infantry 
to  resist  cavalry.  Too  much  attention  cannot  be  paid 
in  teaching  troops  the  use  of  this  arm,  and  inspiring 
them  with  confidence  in  it,  for  it  often  decides  the  fate 
of  a  battle. 

256.  Cutting-arms.  That  edge  of  a  cutting-arm  will 
have  the  greatest  penetration  which  opposes  the  few- 
est points  to  its  object;  a  blade  with  a  convex  edge, 
will,  therefore,  have  greater  penetration  than  a  straight 
one. 

The  effect  of  a  cutting-blade  will  be  modified  by  the 
manner  it  is  applied  to  the  surface  of  the  object;  an 
oblique  stroke,  for  instance,  will  make  a  deej)er  cut 
than  a  direct  one.  If  the  edge  of  the  sharpest  blade  be 
submitted  to  a  microscope,  it  will  present  to  the  eye 
numerous  asperities,  which  give  it  the  appearance  of  the 
cutting  edge  of  a  saw ;  it  is  evident,  therefore,  that  the 
motive  force  should  act  obliquely  to  the  cutting  edge  of 
the  blade,  as  that  enables  it  to  rupture  the  layers  of 
flesh  upon  which  it  acts,  in  detail,  and  without  expend- 
ing its  force  upon  the  elasticity  of  several  layers  at 
once,  which  would  be  the  case  were  it  to  act  directly 
upon  the  object. 


CUTTING- ARMS.  283 

Form  of  the  blade.  When  the  curvature  of  a  blade 
is  convex  on  the  cutting  side,  the  part  near  the  point 
makes  a  deeper  cut  when  it  is  pushed  from  the  hand 
that  moves  it,  as  will  be  the  case  with  the  blows  de- 
livered in  a  charge  of  cavalry.  On  the  contrary,  a  con- 
cave cutting-edge,  like  that  of  a  sickle,  acts  most  favor- 
ably when  it  is  drawn  toward  the  person  using  it ;  such 
is  the  yataghan  of  the  Arabs,  the  shape  of  which  is  that 
of  an  elongated  letter  S. 

Handling.  The  facility  of  handling  a  sabre,  and  the 
effect  of  its  blow,  depend  upon  the  relative  positions 
of  the  handle,  the  centre  of  gravity,  the  point  of  contact, 
and  the  centre  of  percussion. 

The  nearer  the  centre  of  gravity  is  to  the  point  of 
contact,  the  more  powerful  will  be  the  blow ;  but  the 
difficulty  of  handling  increases  with  the  distance  of  the 
centre  of  gravity  from  the  handle.  As  the  force  of  the 
blow  is  the  important  consideration  in  a  sabre,  and 
the  facility  of  handling  in  a  thrusting-sword,  it  is  cus- 
tomary to  make  the  point  of  the  blade  heavier,  and  the 
handle  lighter,  in  the  former  than  in  the  latter. 

In  certain  light  cavalry  sabres,  the  centre  of  gravity 
is  placed  about  three  or  four  inches  from  the  handle. 

In  order  that  no  part  of  the  force  be  lost,  the  point 
of  contact  should  coincide  with  the  centre  of  percus- 
sion ;  the  position  of  the  latter  point,  however,  depends 
upon  the  weight  of  the  soldier's  arm,  if  motion  takes 
place  around  the  shoulder,  and  it  therefore  varies  in 
particular  cases. 

Description.  The  principal  cutting  weapon  is  the 
sabre.  The  cutting  edge  is  generally  convex ;  and  the 
degree  of  its  curvature  is  the  characteristic  feature  of 


284 


SMALL-  AKMS. 


the  weapon.  The  nomenclature  of  the  sabre  is  nearly 
the  same  as  for  the  sword,  the  principal  difference  being 
in  the  structure  of  the  guard,  which  is  made  lighter  or 
heavier,  as  the  sabre  approximates  the  character  of  a 
cutting  or  thrusting  weapon. 

There  are  two  kinds  of  sabres  used  in  the  United 
States  service,  viz.:  the  cavalry  sabre,  and  the  light- 
artillery  sabre. 


Fig.  88. 

The  cavalry-sabre  (fig.  88),  being  used,  to  a  certain 
extent,  for  pointing  as  well  as  cutting,  has  only  a  mod- 
erate degree  of  curvature,  a  long  blade  (36  inches),  and 
a  "basket-hilt"  to  protect  the  hand  from  the  point  of 
the  enemy's  sword,  and  to  carry  the  centre  of  gravity 
toward  the  handle.  The  guard  is  composed  of  the 
front,  middle,  and  bach  branches.  The  gripe  is  covered 
with  calfskin,  and  bound  with  wire. 


Fig.  89. 

The  light-artillery,  sabre  (fig.  89),  being  used  more 
particularly  for  hand-to-hand  conflicts,  has  a  shorter  (32 
inches)  and  more  curved  blade,  and  a  lighter  handle 
than  the  cavalry  sabre.  The  guard  is  composed  of  a 
single  piece  of  brass,  terminating  in  a  scroll. 

The  blades  of  all  sabres  are  grooved,  to  give  them 
lightness.     See  cross-sections  of  figs.  88  and  89. 

257.  Thrusting  and  cutting  arms.  In  certain  services 


SCABBARDS.  285 

it  is  customary  to  arm  the  heaviest  cavalry,  or  cui- 
rassiers, with  swords  which  are  capable  of  coping  with 
the  bayonet  or  lance.  The  blades  are  long  (from  36  to 
40  inches),  light,  and  straight,  and  they  have  a  sharp 
point,  and  a  single  cutting  edge.  The  hilt  is  heavy,  and 
of  the  basket  form. 

The  only  weapon  of 
the  thrusting  and  cut- 
ting class  used  in  the 
United   States    service  Flg* 90* 

is  the  foot  artillery  sword  (fig.  90),  which  resembles  the 
short  Roman  sword  in  its  character.  The  blade  has 
two  cutting  edges,  is  lightened  toward  the  handle,  and 
is  19  inches  long.  The  guard  is  a  simple  cross-piece, 
formed  of  the  same  piece  as  the  handle,  which  is  made 
of  brass. 

258.  Scabbards.  The  objects  of  the  scabbard  are  to 
carry  the  sword,  and  protect  the  blade  from  injury. 
Scabbards  are  generally  secured  to  a  belt,  which  passes 
over  one  of  the  shoulders,  or  around  the  waist  of  the 
wearer. 

For  foot-troops,  scabbards  are  made  of  leather,  mounted 
with  metal  to  protect  them  from  wear.  For  scabbards 
for  mounted  troops,  leather  has  not  sufficient  stiffness 
and  strength,  and  steel  is  used  in  place  of  it.  The 
principal  objections  to  metal  scabbards  are,  that  they 
are  heavy,  dull  the  edge  of  the  blade,  and  make  con- 
siderable noise  in  striking  against  the  equipments  of  the 
horse  and  rider. 

In  certain  parts  of  Asia,  these  objections  are  over- 
come by  making  scabbards  of  wood,  covered  with  leath- 
er or  raw  hide. 


286  SMALL-ARMS. DEFENSIVE    ARMOR. 


DEFENSIVE  ARMOR. 

259.  Cnirass  and  helmet.  The  defensive  armor  of  the 
present  day  consists  of  the  cuirass  and  helmet — the 
former  to  protect  the  breast  and  back ;  and  the  latter, 
the  head  of  the  wearer. 

The  French  cuirass  (fig.  91)  is  composed  of  a  breast- 
plate (a),  and  a  back-piece  (b),  joined 
together  by  straps.  The  thickness  and 
form  of  the  breastplate  are  such  as  to 
ward  off  small-arm  projectiles  beyond  a 
distance  of  forty  yards;  this  distance 
is  assumed  under  the  supposition  that 
Fig.  91.  within  it,  the  infantry  soldier  will    be 

too  busily  engaged  in  preparing  to  defend  himself 
against  the  cavalry  soldier,  with  his  bayonet,  to  fire  his 
piece.  The  back-piece  is  only  made  of  sufficient  thick- 
ness to  resist  the  stroke  of  a  sword ;  it  is  presumed  this 
will  induce  the  wearer  to  present  his  front  rather  than 
his  back,  when  he  arrives  within  a  short  distance  of  his 
enemy.  The  middle  of  the  breastplate  is  formed  into 
a  ridge,  and  the  sides  slope  off  to  reflect  projectiles 
coming  from  the  front.  The  thickness  at  the  ridge  is 
.23  in. ;  from  this,  it  tapers  to  the  edges,  where  it  is 
.078  in.  The  back-piece  is  .047  in.  thick,  throughout, 
and  the  weight  of  the  entire  cuirass  is  about  16.75  lbs. 
The  edges  are  turned  up  to  prevent  the  point  of  a  sword 
from  slipping  off  against  the  body. 

The  cuirass  and  helmet  worn  by  the  leading  sapper  in 
digging  a  siege-trench,  are  thick  enough  in  all  their 
parts  to  resist  a  bullet  at  the  distance  of  40  yards. 


u*^f 


FABRICATION.  287 


MANUFACTURE  OF  SWORD-BLADES,  &c. 


*  ^  260.  Material.  Sword-blades  are  made  of  double 
shear  steel,  or  what  is  better,  of  cast-steel.  A  material 
of  great  toughness  and  elasticity,  as  well  as  hardness,  is 
made  by  forging  together  steel  and  iron,  forming  the 
celebrated  Damascus  steel,  which  is  used  for  sword- 
blades,  springs,  &c.  The  damasked  appearance  is  pro- 
duced by  the  action  of  nitric  acid  and  vinegar,  which 
gives  a  black  tint  to  the  steel  parts,  whilst  the  iron  re- 
mains white. 

261.  Fabrication.  The  operations  of  making  sword- 
blades  are:  1st.  The  preparation  of  the  skelp ;  2d. 
Forging  the  blade;  3d.  Tempering;  4th.  Grinding; 
5th.  Retempering  ;  6th.  Etching ;  7th.  Polishing. 

The  skelp.  The  skelp  is  a  tapering  piece  of  steel  about 
once  and  a  half  as  thick,  two-thirds  as  long,  as  the  pro- 
posed blade,  and  it  is  formed  out  of  a  rectangular  bar 
by  a  trip-hammer. 

Forging.  The  first  operation  is  to  weld  a  piece  on  to 
the  large  end  of  the  skelp  to  form  the  tang.  The  second, 
is  to  draw  it  out  to  the  proper  length  and  thickness. 
The  number  of  heats  required  depends  upon  the  length 
of  the  blade,  and  is  generally  from  seven  to  eight.  The 
second  is  to  stamp  the  grooves.  The  third  is  to  give  the 
bevel  to  the  cutting  edge.  This  operation  necessarily 
elongates  this  edge,  and  gives  a  curved  shape  to  the 
blade,  which  should  be  regulated  to  suit  the  pattern. 
The  blade  is  then  cut  off  to  the  right  length,  and  the 
tang  finished. 

Tempering.     Forged  blades  are  soft  and  flexible  ;  it 


288       SMALL- ARMS. MANUFACTURE    OF    SWORD-BLADES. 

is  necessary,  therefore,  to  give  them  a  certain  degree  of 
hardness  and  elasticity.  This  operation  is  called  hard- 
ening and  tempering,  and  requires  much  tact  on  the 
part  of  the  workman,  in  order  to  detect,  by  the  eye,  the 
temperature  most  suitable  for  the  quality  of  steel  em- 
ployed. 

To  harden  the  blade,  the  workman  holds  it  in  the 
heat  of  a  charcoal  furnace,  moving  it  back  and  forth  to 
heat  the  several  parts  uniformly.  When  its  color  is 
cherry  red,  it  is  withdrawn  and  passed  rapidly  through 
moist  iron  filings,  to  render  the  heat  still  more  uniform, 
and  then  plunged  into  cold  water.  It  is  immediately 
withdrawn  and  examined,  to  see  if  it  be  free  from  the 
coating  of  oxide  which  covers  it  when  taken  out  of  the 
fire. 

The  blade  is  now  very  hard  and  brittle,  and  often- 
times warped ;  it  is  necessary,  therefore,  that  it  should 
be  partially  annealed  or  tempered ;  and,  for  this  pur- 
pose, it  is  again  placed  in  the  furnace  until  the  surface 
is  coated  with  blue  oxide.  In  this  condition  it  is  soft, 
and  in  a  condition  to  be  straightened.  This  is  quickly 
done,  and  the  blade  is  plunged  into  cold  water,  which 
gives  it  the  proper  degree  of  hardness  and  elasticity. 

Grinding.  Grinding  is  done  on  grindstones  which 
revolve  with  great  rapidity — the  object  being  to  reduce 
all  parts  of  the  blade  to  the  proper  size. 

Hetempering.  The  blade  is  partially  bent  and  an- 
nealed by  grinding.  To  correct  these  defects  it  is  again 
heated  to  the  proper  color,  straightened,  and  plunged 
into  cold  water.  If  it  have  lost  too  much  of  its  hard- 
ness, and  be  too  much  bent,  it  should  be  hardened  and 
tempered  as  described  before  grinding. 


PKOOF    OF    BLADE.  289 

Etching.  Etching  is  the  process  of  marking  the  blade 
"with  ornamental  devices,  name  of  maker,  &c.  It  is 
done  by  heating  the  blade  slightly,  and  covering  the 
portion  to  be  marked  with  a  thin  layer  of  beeswax  ;  the 
design  is  marked  on  the  wax  with  a  steel  point,  leaving 
the  metal  bare ;  after  this,  the  design  is  covered  with 
powdered  sea-salt,  and  then  moistened  with  nitric  acid. 
The  acid  acts  only  on  the  bare  parts  of  the  metal,  leav- 
ing them  in  a  rough  state,  while  the  unaffected  part  of 
the  blade  remains  bright. 

Polishing.  The  object  of  polishing  the  blade  is  to 
remove  the  marks  of  the  grindstones,  and  give  it  a 
smooth  finish.  The  polishing  apparatus  is  a  rapidly 
revolving  hard- wood  wheel,  and  the  polishing  material 
is  oil  and  emery.  Burnishing  gives  the  deep,  brilliant 
polish  peculiar  to  steel.  The  operation  is  the  same  as 
in  polishing,  except  that  oil  and  emery  are  replaced  by 
charcoal-dust. 

262.  inspection  of  blades.  The  dimensions  are  com- 
pared with  the  model,  and  verified  by  appropriate 
gauges  and  patterns. 

263.  Proof  of  blade.  The  blade  is  proved  :  1st.  By 
confining  the  point  by  a  staple,  and  bending  the  blade 
over  a  cylindrical  block,  the  curvature  of  which  is  that 
of  a  circle  35  inches  diameter,  the  curvature  of  the  part 
next  the  tang  being  reduced  by  inserting  a  wedge  0.7 
inches  thick  at  the  head,  and  14  inches  long ;  2d.  It  is 
struck  twice  on  each  of  the  flat  sides  on  a  block  of  oak 
wood,  the  curvature  of  which  is  the  same  as  the  above ; 
3d.  It  is  struck  on  the  edge,  and  twice  on  the  back 
across  an  oak  block  one  foot  in  diameter ;  4th.  The 
point  is  placed  on  the  floor,  and  the  blade  bent  until  it 

19 


290  SMALL- ARMS. PORTABLE    FIRE-ARMS. 

describes  an  arc  having  a  certain  versed  sine.  After 
these  trials,  the  blade  is  examined  to  see  that  it  is  free 
from  flaws,  cracks,  or  other  imperfections,  and  that  it  is 
not  set,  that  is  to  say,  does  not  remain  bent. 

The  scabbard  is  proved  by  letting  a  two-pound  weight 
fall  upon  it,  from  the  height  of  18  inches.  The  weight 
should  be  only  one  inch  square  at  the  base ;  the  scab- 
bard should  not  be  indented. 

POKTABLE  FIRE-ARMS. 

264.  Principal  parts.  The  essential  parts  of  all  port- 
able fire-arms  are  the  barrel,  the  lock,  the  stock,  the  sights, 
and  the  mountings.  The  nature  of  the  remaining  parts 
will  be  determined  by  the  manner  of  loading  and  dis- 
charging, as  in  muzzle-loading  and  breec7i-\oadmg  fire- 
arms. Portable  fire-arms  will  be  treated  in  the  same 
order  as  cannon,  viz. :  1st.  The  general  principles 
common  to  the  various  kinds ;  2d.  The  peculiarities 
arising  from  the  uses  to  which  they  are  applied ; 
3d.  The  manufacture,  inspection,  and  treatment  in  ser- 
vice. 

265.  Barrel.  The  barrel  is  the  most  important  part 
of  a  fire-arm,  its  office  being  to  concentrate  the  force  of 
a  charge  of  powder  on  a  projectile,  and  give  it  proper 
initial  velocity  and  direction;  for  these  purposes,  and 
for  the  safety  of  the  firer,  it  should  be  made  of  the  best 
materials,  and  with  the  greatest  care. 

Exterioi\  In  determining  the  exterior  form  of  a  bar- 
rel, it  is  not  only  necessary  to  give  such  thickness  to  the 
different  parts  as  will  best  resist  the  explosive  effort  of 
the  charge,  but  such  as  will  prevent  it  from  being  bent 


BARBELS.  291 

when  used  as  a  pike,  or  subjected  to  the  rough  usage  of 
the  service. 

Weight,  to  a  certain  extent,  is  necessary  to  give  steadi- 
ness to  the  barrel  in  aiming,  and  to  prevent  it  from 
"  springing"  in  firing.  The  latter  defect  generally  arises 
from  bad  workmanship,  whereby  there  is  a  greater  thick- 
ness of  metal,  and,  consequently,  less  expansion,  on  one 
side  of  the  bore  than  the  other.  In  certain  sporting 
rifles,  where  great  accuracy  is  sought  to  be  obtained,  the 
barrel  is  made  to  weigh  from  12  to  15  lbs. ;  but  in  the 
military  service,  where  it  is  carried  by  the  soldier,  it 
seldom  weighs  more  than  5  lbs. 

The  thickness  of  metal  of  the  rifle-musket  barrel  at 
the  breech  is  0.28  inch;  from  this  point  it  gradually 
diminishes  (the  exterior  element  being  a  slightly  re- 
entering curve)  to  the  muzzle,  which  is  0.1  inch. 


Fig.  92. 

Nomenclature.  The  principal  parts  of  a  barrel  (see 
fig.  92)  are  the  breech,  the  breech-screw  (1)  ;  the  flats  (3), 
bevels  (2),  and  oval;  the  cone,  and  cone-seat  (4);  the 
bayonet-stud  and  front-sights  (5)  ;  the  bore,  the  grooves, 
and  the  lands  (6). 

The  breech-screw  is  composed  of  the  body  (a),  tenon 
(b),  and  tang  (c).  The  object  of  the  breech-screw  is  to 
close  the  bottom  of  the  bore ;  the  tenon  fits  into  a  mor- 
tise cut  in  the  stock,  and  prevents  the  barrel  from  turn- 
ing in  its  bed ;  the  tang  is  the  part  by  which  the  breech 
of  the  barrel  is  secured  to  the  stock,  and,  for  this  pur- 


292  SMALL- ARMS. PORTABLE    FIRE-ARMS. 

pose,  it  is  pierced  with  a  hole  for  the  tang-screw,  which 
passes  through  the  stock,  and  screws  into  the  guard- 
plate. 

The  fiats  are  two  vertical  plane  surfaces,  situated  at 
equal  distances  from  the  axis  of  the  bore.  They  serve 
to  prevent  the  barrel  from  turning  in  the  jaws  of  the 
vice  when  the  breech-screw  is  taken  out ;  the  flat,  on 
the  right  side  of  the  barrel,  also  presents  a  surface  of 
contact  for  the  lock-plate,  which  prevents  the  hammer 
and  cone  from  changing  their  relative  position. 

The  corners  of  the  flats  are  bevelled  to  prevent  the 
barrel  from  being  marred,  and  to  improve  its  finish. 

The  cone.  The  functions  of  the  cone  are 
to  support  the  percussion-cap  when  exploded 
by  the  hammer,  and  to  conduct  the  flame  to 
the  vent  of  the  piece.    The  parts  (see  Hg.  93) 

Fig.  93.  are  the  nipple  ,(1),  upon  which  the  cap  is 
placed;  the  square  (2),  the  part  to  which  the  wrench 
is  applied ;  the  shoulder  (3) ;  the  screw-thread  (4) ;  and 
the  vent  (5). 

To  increase  the  effect  of  the  hammer  on  the  cap,  the 
upper  surface  of  the  cone  is  diminished  by  chamfering 
the  corners. 

The  cone-seat  is  a  projecting  piece  of  iron  welded  to 
the  barrel,  near  the  breech,  for  the  purpose  of  sustaining 
the  cone.  The  principal  parts  are  the  female  screw,  the 
vent,  and  the  rim ;  the  latter  prevents  the  flame  from 
penetrating  between  the  lock  and  barrel.  The  position 
of  the  cone-seat  should  be  such  that  the  vent  will  have 
a  direct  communication  with  the  bore.  In  the  present 
barrel,  however,  the  vent  makes  a  bend  at  right  angles 
with  the  axis  of  the  cone,  on  account  of  the  peculiar 


BAEEELS.  293 

construction  of  the  new  self-priming  lock.  To  prevent 
the  blow  of  the  hammer  from  straining  the  cone,  and 
breaking  it  off  in  the  cone-seat,  the  plane  of  the  face  of 
the  hammer  should  pass  through  the  axis  of  motion. 

Calibre.  Three  important  points  are  to  be  considered 
in  determining  the  calibre  of  small-arms:  1st.  The 
calibre  should  be  as  small  as  possible,  to  enable  the 
soldier  to  carry  the  greatest  number  of  cartridges; 
with  the  present  calibre,  the  number  of  musket-car- 
tridges is  limited  to  40 ;  the  total  weight  of  which  is 
about  3^  lbs.  2d.  To  diminish  the  amount  of  ammu- 
nition required  to  supply  the  wants  of  an  army,  and  to 
prevent  the  confusion  that  is  liable  to  arise  from  a  va- 
riety of  calibres,  there  should  not  be  more  than  two,  for 
all  arms  of  the  same  service,  viz.,  one  for  the  musket 
and  one  for  the  pistol.  3d.  This  point  relates  to  the 
force  and  accuracy  of  the  projectile.  The  introduction 
of  elongated  projectiles  affords  the  means  of  increasing 
the  accuracy  and  range  of  fire-arms,  without  increasing 
the  weight  of  the  projectile,  simply  by  reducing  the  cal- 
ibre, which  diminishes  the  surface  opposed  to  the  air. 
Too  great  reduction  of  calibre,  however,  gives  a  very 
long  and  weak  projectile ;  and  besides,  the  effect  of  a 
projectile  on  an  animate  object,  depends  not  only  on 
its  penetration,  but  on  the  shock  communicated  by  it 
to  the  nervous  system,  or  upon  the  surface  of  contact. 
A  projectile  of  very  small  calibre,  having  but  little  iner- 
tia, does  not  expand  well  into  the  grooves  of  the  bore, 
by  the  action  of  the  powder ;  it  is  not,  therefore,  suited 
to  the  present  method  of  loading,  at  the  muzzle. 

The  foregoing  considerations  led  to  a  general  reduc- 
tion of  calibre  on  the  introduction  of  rifles  for  military 


294  SMALL- ARMS. PORTABLE    FIRE-AEMS. 

purposes.     The  present  rifle  calibre  is  .58  inch ;  that  of 
the  pistol  (navy  size)  is  .37  inch. 

Length  of  barrel.  The  length  of  a  gun-barrel  is  de- 
termined by  the  nature  of  the  service  to  which  it  is 
applied,  rather  than  by  the  effect  which  it  exerts  on 
the  force  of  the  charge.  It  has  been  shown  by  experi- 
ment, that  the  velocity  of  a  projectile,  in  a  smooth- 
bored  musket,  increases  with  the  length  of  the  bore,  up 
to  108  calibres,  at  least ;  but  a  musket  with  this  length  of 
barrel,  would  be  too  heavy  as  a  fire-arm,  and  too  un- 
wieldy as  a  pike.  The  length  of  the  present  musket- 
barrel  is  TO  calibres,  or  40  inches. 

Grooves.  The  principal  cause  of  the  deviation  of  a 
projectile  from  its  true  line  of  flight  is  the  rotary  motion 
which  it  receives  in  the  bore  of  the  piece,  combined 
with  the  resistance  of  the  air.  In  a  smooth-bored  bar- 
rel, variable  causes  conspire  to  produce  rotation,  conse- 
quently the  deviation  which  results  from  it,  is  variable 
and  uncertain.  In  addition,  therefore,  to  giving  a  pro- 
jectile the  requisite  initial  velocity  and  direction,  a  gun- 
barrel  should  be  constructed  to  give  it  a  certain  rotary 
motion  that  shall  continue  throughout  its  flight.  This 
rotary  motion,  for  reasons  stated  in  discussing  rifle-can- 
non, takes  place  around  an  axis  coinciding  with  that  of 
the  barrel,  and  is  produced  by  spiral  grooves  cut  on  the 
surface  of  the  bore. 

The  points  to  be  observed  in  constructing  rifle-grooves 
for  military  arms,  are  range,  accuracy  of  fire,  endurance, 
and  facility  of  loading  and  cleaning  the  bore.  For  ex- 
panding projectiles,  experiment  shows  that  these  points 
are  best  attained  by  making  the  grooves  broad  and  shal- 
low, and  with  a  moderate  twist. 


lock.  295 

The  following  is  a  description  of  the  grooves  adopted 
by  the  United  States  government,  viz. : 

Number.     Three. 

Width,  Eqnal  to  the  lands,  or  one-sixth  the  circum- 
ference of  the  bore. 

Depth.  Uniformly  decreasing  from  the  breech,  where 
it  is  .015  in.,  to  the  muzzle,  where  it  is  .005  inch. 

Twist.  Uniform,  one  turn  in  six  feet  for  long  or 
musket,  and  one  turn  in  four  feet  for§  short  or  carbine 
barrels. 

The  effect  of  decreasing  the  depth  of  rifle-grooves  is 
to  increase  the  accuracy,  but  diminish  the  range.  The 
increase  of  accuracy,  undoubtedly,  arises  f.om  the  fact 
that  the  projectile  is  held  more  firmly  by  the  grooves, 
as  it  passes  along  the  bore;  while  the  diminution  of 
range  arises  from  an  increase  of  friction  between  the 
projectile  and  the  grooves. 

The  twist  is  dependent  on  the  length,  diameter,  and 
initial  velocity  of  the  projectile;  in  other  words,  it 
should  be  increased  in  a  certain  proportion  to  the  length 
of  the  projectile;*  and  for  the  same  weight  of  projectile, 
it  should  be  increased  in  a  certain  proportion  as  the 
length  of  the  bore  is  diminished.  Experiment,  how- 
ever, is  the  surest  way  of  determining  the  most  suitable 
twist  for  any  projectile. 

266.  L.ocfc.  The  lock  is  the  machine  by  which  the 
charge  in  the  barrel  is  ignited.  Nearly  all  the  locks  of 
the  present  day  belong  to  the  percussion  class,  in  which 
fire  is  produced  by  the  blow  of  a  hammer  upon  a  small 
charge  of  percussion  powder  contained  in  a  copper  or 
paper  cap. 

*  See  section  on  rifle-cannon. 


296  SMALL- ARMS. PORTABLE    FIRE-ARMS. 

The  conditions  to  be  fulfilled  in  the  construction  of 
a  military  lock,  are — 

1st.  The  production  of  fire,  and  its  communication 
with  the  charge,  should  be  certain,  and  under  the  per- 
fect control  of  the  soldier. 

2d.  The  cap  should  be  placed  upon  the  cone  with 
facility,  and  it  should  not  be  displaced  in  handling  the 
piece. 

3d.  Fragments  of  the  cap  should  not  incommode  per- 
sons near  by,  nor  should  the  gas  generated  by  the  explo- 
sion of  the  cap  corrode  or  injure  the  cone,  barrel,  or  stock. 

4th.  There  should  be  no  danger  of  accidental  ex- 
plosions. 

Nomenclature.  The  ordinary  percussion  lock  is  com- 
posed (see  Hg.  94)  of  the  lock-plate  (1),  to  which  the 
several  parts  are  attached, 
and  by  which  the  lock  is 
fastened  to  the  stock;  the 
hammer  (2),  which  strikes 
upon  the  cap,  and  explodes 
the  composition ;  the  main-  Fte- 94- 

spring  (3),  which  sets  the  hammer  in  motion;  the  tum- 
bler (4),  or  axle,  by  which  the  power  of  the  main-spring 
is  communicated  to  the  hammer ;  the  sear  (5),  or  lever, 
the  point  of  which  fits  into  the  notches  of  the  tumbler, 
and  holds  the  hammer  in  the  required  position;  the 
notches  are  designated  as  the  full-cock  notch,  and  safety- 
notch;  the  sear-spring  (6),  which  presses  the  point  of 
the  sear  into  the  tumbler  notch ;  the  bridle  (omitted  in 
the  figure),  which  is  pierced  with  two  holes  for  the  inner 
pivots  of  the  sear  and  tumbler ;  the  swivel  (7),  which 
joins  ttie  main-spring  and  tumbler. 


lock.  297 

Self-priming.  The  foregoing  constitute  the  essential 
parts  of  an  ordinary  percussion-lock ;  in  addition  to 
these,  the  new  service  lock  is  supplied  with  Maynard's 
self-priming  apparatus.*  The  primer  used  in  this  ap- 
paratus, is  a  long  strip  of  paper  containing  about  60 
charges  of  percussion-powder,  distributed  at  uniform 
intervals.  The  strip  is  wound  up  in  the  form  of  a  coil, 
and  inserted  in  a  cavity  cut  into  the  exterior  surface 
of  the  lock-plate,  called  the  magazine.  One  end  of  the 
coil  protrudes  through  an  opening  in  the  magazine  (8), 
so  that  the  centre  of  the  first  charge  of  percussion- 
powder  is  directly  over,  but  not  in  contact  with,  the  top 
of  the  cone.  When  the  lock  is  sprung,  the  primer  is  cut 
off  by  a  knife-edge  on  the  lower  side  of  the  face  of 
the  hammer,  carried  forward  and  exploded  on  the  top 
of  the  cone.  A  feeding- finger  (9),  connected  with  the 
tumbler,  pushes  out  another  primer,  when  the  hammer 
is  brought  to  the  position  of  "  full-cock." 

Other  methods  are  used  for  self-priming,  in  some  of 
which  the  primer  is  enclosed  in  th  cartridge  itself;  but 
few  are  found,  under  all  circumstances,  to  be  as  reliable 
as  the  common  percussion  lock. 

Back-action.  In  the  back-action  lock,  the  main-spring 
is  placed  in  rear  of  the  tumbler,  and  the  sear-spring,  as 
a  separate  part,  is  dispensed  with.  The  mortise,  which 
forms  a  bed  for  this  lock,  seriously  affects  the  strength 
of  the  stock  at  the  handle ;  and,  for  this  reason,  the 
front-action  lock  is  generally  preferred  for  military 
arms. 

'Accidents.     If  the  head  of  the  hammer  be  allowed  to 


*  In  1861,  the  self-priming  apparatus  was  omitted  in  all  arms  of  the  U.  S.  ser- 
vice, as  it  was  not  found  to  work  well  in  practice. 


298  SMALL- ARMS.- — PORTABLE    FIRE-ARMS. 

rest  on  the  cap,  an  explosion  will  be  liable  to  follow  an 
accidental  blow  on  the  hammer. 

267.     stock.     The  stock  i3  the  wooden  part  of  a  fire- 
arm, to  which  all  the  parts  are  assembled. 


Fig.  95. 

The  most  important  portions  of  the  stock  (see  fig.  96) 
are  the  butt  (1),  the  handle  (2),  the  head  (3),  the  grease- 
box*  (4),  the  beds  for  the  barrel,  lock,  band-springs,  guard- 
plate,  butt-plate;  the  shoulders  for  the  tip  and  bands, 
and  the  rarnrod-groove. 

The  material  of  the  stock  should  be  light  and  strong. 
Well-seasoned  black  walnut  is  generally  used  for  mili- 
tary small-arms. 

The  butt  is  intended  to  rest  against  the  shoulder,  and 
support  the  recoil  of  the  piece ;  it  should  be  of  such 
length  and  shape  as  will  enable  it  to  transmit  the  recoil 
with  the  least  inconvenience  to  the  soldier.  The  longer 
it  is,  to  a  certain  extent,  the  more  firmly  will  it  be  press- 
ed against  the  shoulder,  and  the  effect  of  the  recoil  will 
be  a  push  rather  than  a  blow.  The  stock  is  crooked  at 
the  handle,  for  convenience  in  aiming,  and  for  the  pur- 
pose of  diminishing  the  direct  action  of  the  recoil. 
Changing  the  direction  of  the  recoil,  in  this  manner, 
causes  the  piece  to  rotate  around  the  shoulder  with  an 
intensity  proportional  to  the  lever  arm  a  b  /  whence  it 
follows  that,  if  the  stock  be  made  too  crooked,  the  butt 
will  be  liable  to  fly  up  and  strike  the  soldier's  face. 

268.  Sights.  The  sights  are  guides  by  which  the  piece 

*  Omitted  in  1861. 


SIGHTS.  299 

is  given  the  elevation  and  direction  necessary  to  hit  the 
object.     There  are  two,  called  front  and  rear  sights. 

The  front  sight  is  fixed ;  in  the  rifle-musket  it  is 
formed  by  sharpening  the  top  of  the  bayonet-stud,  so 
that  its  edge  shall  present  a  point  to  the  eye  of  the 
marksman.  The  fineness  of  this  point  is  regulated  by 
the  length  of  the  barrel,  or  distance  from  the  eye,  and 
the  size  and  distance  of  the  objects  generally  aimed  at; 
it  is  made  coarser  in  military  than  in  sporting  arms,  to 
prevent  injury. 

The  rear  sight  is  composed  of  a  base,  which  is  firmly 
secured  to  the  barrel  at  a  short  distance  from  the  breech, 
and  a  movable  part  capable  of  being  adjusted  for  dif- 
ferent elevations  of  the  barrel.  The  sight  originally 
affixed  to  the  rifle-musket  had  a  single  leaf,  to  which 
was  attached  a  slide,  containing  the  sight  notch,  which 
could  be  adjusted  for  all  distances  between  100  and 
1,000  yards.  By  a  late  order  of  the  war  department, 
this  has  been  replaced  by  a  sight  which  has  three  mov- 
able leaves,  turning  on  a  common  axis,  and  bearing 
notches  adjusted  to  100,  300,  and  500  yards,  respect- 
ively. 

Aiming  a  fire-arm  consists  in  bringing  the  top  of  the 
front  sight,  and  the  bottom  of  the  notch  of  the  rear 
sight,  into  the  line,  joining  the  eye  and  the  object.  A 
sight  for  a  military  arm  should  satisfy  the  following 
conditions,  viz. :  1st.  It  should  be  easily  adjusted  for  all 
distances  within  effective  range;  2d.  The  form  of  the 
notch  should  permit  the  eye  to  catch  the  object  quickly ; 
3d.  It  should  not  be  easily  deranged  by  the  accidents 
of  the  service. 

The  globe  and  telescopic  sights  are  used  for  very  accu- 


300  SMALL-AEMS. PORTABLE    FIRE-ARMS. 

rate  sporting-arms,  but  they  are  too  delicate  in  their 
structure,  and  too  slow  in  their  operation,  for  general 
purposes. 

In  the  absence  of  a  proper  rear  sight,  the  soldier  of 
the  line  may  be  taught  to  point  his  piece  by  aiming 
over  the  centre  of  the  knuckle  of  his  left  thumb ;  the 
position  of  the  thumb  along  the  barrel  determines  the 
elevation  of  the  piece.  This  method  is  practised  by 
certain  French  troops  of  the  line,  for  distances  less  than 
400  yards. 

269.  Mountings  The  mountings  comprise  the  butt- 
plate,  the  guard-plate,  the  bands,  springs,  and  tip. 

The  butt-plate  protects  the  end  of  the  stock  from  in- 
jury by  contact  with  the  ground ;  it  is  curved  to  fit  the 
shoulder  in  firing,  and  is  secured  in  its  place  by  two 
wood-screws. 

The  guardplate  strengthens  the  handle  of  the  stock, 
and  serves  as  a  fulcrum  for  the  trigger.  It  is  secured 
by  the  tang-screw  and  two  wood-screws. 

The  trigger  is  a  lever  used  to  disengage  the  point  of 
the  sear  from  the  notch  of  the  tumbler,  which  sets  the 
lock  in  motion.  The  force  required  to  set  off  the  trig- 
ger, if  very  great,  may  disturb  the  accuracy  of  the 
aim ;  if  it  be  slight,  the  piece  will  be  liable  to  accidental 
discharges,  as  in  the  case  of  the  hair-trigger  used  in 
target-pieces. 

The  guard-bow  protects  the  finger-piece  of  the  trigger 
from  injury,  and  from  accidental  blows  that  might  pro- 
duce explosions. 

The  bands  secure  the  barrel  to  the  stock,  and  the 
springs  keep  the  bands  in  their  places.  If  the  piece  be 
intended  to  be  carried  upon  the  soldier's  back,  it  is  pro- 


BREECH-LOADING    ARMS.  301 

vided  with  two  swivels,  one  of  which  is  fastened  to  the 
guard-bow,  and  the  other  to  a  band. 

270.  Ramrod.  The  ramrod  is  the  long,  slender  piece 
employed  in  muzzle-loading  arms,  to  push  the  charge  to 
its  proper  place,  and  to  wipe  out  the  barrel.  It  is 
carried  in  a  groove  cut  into  the  under  side  of  the  stock, 
and  it  is  kept  in  its  place  by  the  pressure  of  the  swell 
against  the  tip  of  the  stock.  The  head  of  the  rod  is 
countersunk  to  fit  the  point  of  the  projectile ;  and  the 
point  has  a  screw  to  receive  the  wiper  and  ball-screw — 
implements  that  are  used  to  clean  and  remove  obstruc- 
tions from  the  bore. 


x^ 


BREECH-LOADING  ARMS. 


271.  General  description.  The  term  "  breech-loading" 
applies  to  those  arms  in  which  the  charge  is  inserted  into 
the  bore  through  an  opening  in  the  breech ;  and,  as  far 
as  loading  is  concerned,  the  ramrod  is  dispensed  with. 

The  interior  of  the  barrel  of  a  breech-loading  arm,  is 
divided  into  two  distinct  parts,  viz.,  the  bore  proper,  or 
space  through  which  the  projectile  moves  under  the  in- 
fluence of  the  powder ;  and  the  chamber  in  which  the 
charge  is  deposited.  The  diameter  of  the  chamber  is 
usually  made  a  little  larger,  and  that  of  the  bore  a  little 
smaller,  than  that  of  the  projectile ;  this  arrangement 
facilitates  the  insertion  of  the  charge,  and  causes  the 
projectile  to  be  compressed,  and  held  firmly  by  the 
lands  in  its  passage  through  the  bore.  As  before 
stated,  this  operation  is  called  slugging  the  projectile. 
The  bottom  of  the  grooves,  and  the  surface  of  the  cham- 
ber, are  continuous. 


302  SMALL-ARMS. BREECH-LOADING. 

272.  Closing  the  breech.  The  distinguishing  feature 
of  a  breech-loading  arm  is  the  method  of  closing  the 
breech.  The  systems  at  present  used  may  be  referred 
to  two  classes — those  with  movable  chambers,  and  those 
with  faced  chambers. 

The  movable  chamber  is  formed  in  a  separate  piece 
from  the  barrel,  and  the  joint,  or  opening,  is  necessarily 
in  front  of  the  charge  ;  the  fixed  chamber  is  formed  by 
counterboring  the  bottom  of  the  bore,  and  the  opening 
is  in  rear  of  the  charge.  As  a  general  rule,  the  mechan- 
ism of  the  fixed  chambered  pieces  is  stronger  and  sim- 
pler than  that  of  movable  chambered  pieces,  and  is, 
therefore,  to  be  preferred,  for  military  purposes. 

273.  Escape  of  gas.  One  of  the  most  serious  defects 
of  breech-loading  arms  was  the  escape  of  gas  through 
the  joint;  this  not  only  incommoded  the  soldier  and  his 
comrades,  but  seriously  interfered  with  the  working  of 
the  machinery,  and  the  accuracy  and  force  of  the  fire. 
The  great  attention  that  has  been  paid  to  the  subject 
of  breech-loading  arms,  in  the  last  few  years,  has  led  to 
an  improvement  which  entirely  removes  this  defect,  and 
this  consists  in  closing  the  joint  at  the*  moment  of  dis- 
charge, by  the  action  of  the  gas  itself.  This  operation, 
which  is  called  "  packing  the  joint,"  is  now  accomplished 
in  a  variety  of  ways,  all  of  which  may  be  divided  into 
two  general  methods:  1st.  By  the  use  of  a  cartridge- 
case  of  sheet-brass,  India-rubber,  or  other  material ;  2d. 
By  the  use  of  a  thin  elastic  ring  of  metal  which  over- 
lies the  joint.  By  the  first  method,  the  case  is  perma- 
nently distended,  and  some  arrangement  is  required  to 
remove  it  from  the  chamber.  Generally  speaking,  the 
case  is  not  so  much  injured  but  that  it  can  be  safely 


SHARP'S    SYSTEM. 


303 


used  for  several  fires.     In  the  second  method,  the  ring, 

or  gas-check,  is   a  part  of  the  arm  ;  and  its  elasticity 

causes  it  to  return  to  its  original  form  after  the  discharge. 

274.     Burn§ide'§  system.     An  example  of  the  first 

method     is    shown    in 

This 

96)  has 

chamber, 

by  turn- 


Burnside's   arms 
piece   (see  Hg 
a     movable 
which   opens 


Fig.  96. 

ing  on  a  hinge  (a).  The  joint  (b)  through  which  the 
gas  tends  to  escape  is  covered  by  the  embossed  portion 
of  a  thin  brass  cartridge-case,  which  packs  the  joint, 
and  cuts  off  the  escape  of  gas.  The  case  is  made  coni- 
cal, that  it  may  be  easily  disengaged  from  the  chamber 
by  the  movable  pin  (<?),  after  firing. 

The  small  end  of  the  case  has  a  hole  for  the  passage 
of  the  flame  from  the  cap,  which  is  closed  with  wax  to 
protect  the  powder  from  moisture.  A  leather  wad  and 
a  small  quantity  of  grease  are  placed  between  the  pow- 
der and  ball,  to  soften  and  remove  the  dirt  from  the 
bore  after  each  discharge. 

The  advantages  of  this  class  of  guns  are,  the  strength 
and  water-proof  nature  of  the  cartridges,  a  perfectly 
tight  joint,  and  entire  freedom  in  the  working  of  the 
machinery.  The  principal  disadvantage  is  the  cost  and 
peculiarity  of  the  cartridge. 

275.  Sharp's  system.  This 
carbine  (see  fig.  97)  has 
a  fixed  chamber,  and  the 
breech  is  closed  by  a  slide 
(a)  which  moves  nearly  at 
rig.  97.  a  right-angle  to  the  axis  of 


304  SMALL-ARMS. BREECH-LOADING. 

the  barrel.  Formerly  there  was  no  attempt  made  to 
prevent  the  escape  of  gas  through  the  joint,  and  great 
difficulty  was  experienced  in  working  the  slide,  after  a 
few  discharges  in  very  dry  weather.  By  boring  a  re- 
cess into  the  face  of  the  slide,  opposite  to  the  chamber, 
and  inserting  a  tightly -fitting  ring  (b  />)  into  it,  in  such 
manner  that  the  inner  rim  is  pressed  against  the  end  of 
the  barrel  at  the  instant  of  discharge,  the  escape  of  the 
gas  is  prevented. 

This  piece  is  loaded  by  depressing  the  lever  which 
withdraws  the  slide  and  opens  the  breech.  The  car- 
tridge is  inserted,  the  bullet  penetrates  as  far  as  the 
shoulder  of  the  chamber,  leaving  a  portion  of  the  paper 
and  powder  projecting;  this  is  cut  off  by  the  upward 
motion  of  the  slide,  and  the  powder  is  exposed  to  the 
action  of  the  cap.  A  portion  of  the  chamber,  surround- 
ing the  bullet,  is  enlarged  in  diameter  (cc)y  in  order 
that  the  accumulation  of  dirt  may  not  prevent  the 
bullet  from  being  pushed  forward  to  its  place,  and 
thereby  increasing  the  amount  of  powder  cut  off  by 
the  slide. 


1                    ■   /                            * 

I      ...     c                  d  :         \    ■:■    ■                                       ~i 

h                                                             J 2 

Fig.  98. 

276.  Maynard'§  system.  The  chamber  (a),  (see  fig. 
98)  of  the  Maynard  carbine,  is  fixed.  The  barrel  is 
hinged  to  the  stock,  and,  by  means  of  a  lever,  which 
also  serves  as  the  trigger-guard,  the  breech  is  raised  to 
receive  the  cartridge,  and  lowered  to  close  it.  The  car- 
tridge-case (<?)  is  made  of  brass,  or  other  elastic  metal, 


maynaed's  system.  305 

and  is  cylindrical  in  shape.  It  has  a  flange  (£)  soldered 
to  the  bottom,  to  facilitate  handling,  and  the  vent  is  in 
the  centre  of  the  bottom. 

The  bullet  (d)  is  solid  at  the  base ;  it  is  cylindrical 
as  far  as  it  is  inserted  into  the  cartridge-case,  thence 
tapers  ovoidally  to  the  front,  and  terminates  in  a  flat 
surface  perpendicular  to  the  axis.*  It  has  but  one 
groove  in  the  cylindrical  part,  which  contains  the  lubri- 
cant. The  diameter  of  the  bullet  is  equal  to  that  of 
the  bore,  plus  the  depth  of  the  grooves.  In  charging 
the  cartridge,  the  bullet  is  set  with  its  axis  coincident 
with  the  axis  of  the  cartridge ;  it  is,  therefore,  coinci- 
dent with  that  of  the  bore,  when  the  piece  is  loaded. 
There  being  no  hollow  in  the  base  of  the  ball,  there  is 
ho  unequal  expansion  to  change  the  position  of  its  axis 
while  in  the  gun;  the  bullet,  therefore,  leaves  the  gun 
in  the  proper  direction.  The  barrel  may  be  said  to  act  the 
part  of  a  die  to  give  each  bullet  the  same  form  and  size. 

In  loading  the  cartridge,  the  bullet  is  not  pressed 
upon  the  powder — the  fire  from  the  primer  entering  the 
vent  more  freely  when  the  powder  is  loose.  The  vent 
of  the  cartridge,  which  is  very  small,  is  closed  by  a 
small  quantity  of  the  lubricant,  which  does  not  impede 
the  passage  of  the  flame,  as  it  is  driven  into  the  case  by 
the  confined  air  in  advance  of  the  flame. 

The  cartridge  expands  from  the  pressure  within,  so 
as  to  cut  off  all  escape  around  it ;  being  elastic,  and  the 
expansion  being  within  the  elastic  limit,  it  contracts  so 

*  By  this  means,  it  is  thought  that  the  air  is  deflected  more  effectually  from  the 
sides  of  the  projectile,  and  the  friction  which  opposes  rotation  is  diminished.  It  is 
not  found  to  detract  from  the  range,  a  fact  which  favors  the  existence  of  Newton's 
theoretical  solid  of  least  resistance,  which  is  likewise  terminated  with  a  plane  aur* 
face. 

20 


306  SMALL- ARMS. BREECH-LOADING. 

sa  to  be  easily  withdrawn;  and,  as  it  is  supported  on 
all  sides  when  fired,  it  is  not  injured  by  use. 

The  only  instrument  required  for  loading  the  case  is 
a  tube  closed  at  one  end,  by  a  bottom  shaped  like  the 
front  end  of  the  bullet — as  large  internally  as  the  car- 
tridge, and  weighing  about  two  ounces. 

The  Maynard  musket,  for  using  the  same  system  of 
ammunition,  is  like  the  ordinary  musket,  in  every  par- 
ticular except  that  an  oblong  opening  is  made  in  the 
upper  side  of  the  barrel,  extending  from  the  front  end 
of  the  breech-pin  1.3  in.,  into  which  opening  is  fitted  a 
solid  block,  hinged  to  the  left  side  of  the  barrel  and 
filling  the  bore,  so  as  to  be,  in  effect,  a  movable  exten- 
sion of  the  breech-pin.  The  barrel  is  chambered  for 
the  cartridge.  The  hinged  block  is  the  cone-seat.  By 
turning  the  cone-seat  over  to  the  left,  the  barrel  is 
opened  so  that  the  cartridge  may  be  inserted.  By 
turning  it  back  again  the  cartridge  is  secured  in  place, 
and  the  vent  from  the  cone  is  brought  in  apposition 
with  that  of  the  cartridge.  Instead  of  a  flange  on  the 
cartridge,  to  facilitate  handling,  there  projects  from  the 
bottom  a  short  arm,  or  a  thong,  which  is  received  into 
a  notch  in  the  side  of  the  barrel.  There  being  only  a 
direct  backward  pressure  upon  the  cone-seat  (which  is 
resisted  by  the  breech-pin),  a  simple  snap-bolt  keeps  it 
in  place.  With  an  empty  cartridge  case  in  the  chamber, 
this  forms  a  muzzle-loading  arm  for  ordinary  ammu- 
nition— an  advantage  of  importance  under  some  cir- 
cumstances. It  is  asserted  that  this  musket  can  be 
made  as  cheaply  as  the  ordinary  one,  and  it  has  been 
shown  that  the  ordinary  one  can  be  changed  to  this 
system,  so  as  to  be  neat  in  appearance,  strong,  and 


SMALL-ARM   PROJECTILE.  307 

simple,  and  at  a  very  small  cost.  The  opening  in  the 
barrel  facilitates  greatly  the  perfect  cleaning  and  in- 
spection of  the  bore — points  of  much  importance. 

The  foregoing  breech-loading  arms  are  particularly 
referred  to  for  the  purpose  of  illustrating  the  principles 
of  the  classification,  and  because  their  peculiar  merits 
have  been  established,  and  the  pupil  will  be  likely  to 
meet  with  them  in  service. 

277.  Advantages,  &c.  The  advantages  of  breech-load- 
ing over  muzzle-loading  arms  are :  1st.  Greater  security 
from  accidents  in  loading ;  2d.  The  impossibility  of  get- 
ting more  than  one  cartridge  in  the  piece  at  the  same 
time ;  3d.  Greater  facility  of  loading,  under  all  circum- 
stances, and  particularly  when  the  soldier  is  mounted,  or 
is  lying  upon  the  ground  ;  4th.  The  security  with  which 
the  charge  is  kept  in  its  place  when  the  piece  is  carried 
on  horseback  with  the  muzzle  down. 

The  disadvantage  of  breech-loading  arms  is  the  com- 
plicated nature  of  the  machinery,  and  their  consequent 
want  of  strength  and  solidity  when  subjected  to  rough 
usage.  It  cannot  be  denied  that,  in  spite  of  this  disad- 
vantage, breech-loading  arms  are  steadily  progressing 
in  favor  for  the  mounted  service,  and  in  some  European 
services  they  are  used,  to  a  certain  extent,  by  foot  troops 
of  the  line. 

SMALL-AKM  PKOJECTILES. 

278.  Forcing.  "Forcing,"  as  applied  to  a  projectile, is 
the  operation  by  which  it  is  made  to  take  hold  of  the 
grooves  of  a  rifled  barrel,  and  follow  them  in  its  passage 
through  the  bore.  It  may  be  accomplished  in  various 
ways,  most  of  which  depend  upon  the  soft  and  yielding 


308  SMALL-ARMS. PROJECTILES. 

nature  of  lead,  the  material  of  which  small-arm  projec- 
tiles are  made,  viz. : 

1st.  By  the  action  of  the  ramrod. 

2d.  By  the  action  of  the  powder. 

3d.  By  the  action  of  ramrod  and  powder  combined. 

4th.  By  the  form  of  the  bore  or  projectile,  as  in 
breech-loading  arms,  <fcc. 

279.  By  the  action  of  the  ramrod.  When  rifles  were 
first  made,  forcing  was  effected  by  making  the  projectile 
a  little  larger  than  the  bore,  and  driving  it  down  with  a 
mallet  applied  to  the  point  of  the  ramrod;  although 
this  caused  the  lead  to  fill  the  grooves  completely,  con- 
verting the  projectile  into  a  screw,  whereof 
the  barrel  was  the  nut ;  the  operation  was 
slow  and  laborious,  and  the  accuracy  of  the 
projectile  was  impaired  by  the  consequent 

Fig.  99.        disfiguration. 

The  form  of  the  grooves  then  used  is  shown  in  Hg.  99. 
They  were  liable  to  be  injured  by  the  ramrod,  and  were 
difficult  to  clean. 

280.  Patch.  The  foregoing  plan  was  improved  by 
making  a  projectile  a  little  smaller  than  the  bore,  and 
wrapping  it  with  a  patch  of  cloth,  greased,  to  diminish 
friction  in  loading.  The  thickness  of  the  cloth  was 
greater  than  the  windage;  this  caused  the  patch  to 
press  upon  the  projectile  with  so  much  force  as  to  com- 
pel it  to  follow  the  winding  of  the  grooves  without  ma- 
terially altering  its  shape.  The  patch  is  still  used  in 
sporting  rifles,  and  gives  excellent  results ;  but  the  load- 
ing is  too  slow  and  difficult  for  a  military  arm. 

281.  Deivigne'§  plan.  M.  Delvigne,  an  officer  of  the 
French  infantry,  appears  to  have  been  the  first  person 


TIGE,    OR    SPINDLE.  309 

who  overcame  the  difficulty  of  loading  rifles,  thereby  re- 
moving the  principal  obstacle  to  their  introduction  into 
the  military  service.  The  plan  proposed  by  him,  in 
1827,  was  to  make  the  projectile  small  enough  to  enter 
the  bore  easily,  and  to  attach  it  to  a  sabot,  or  block  of 

wood  (a,  fig.  100),  which,  when 
in  position,  rested  upon  the 
the  shoulders  of  a  cylindrical 
chamber  (b),  formed  at  the  bot- 
Fig- 10°-  torn  of  the  bore,  to  contain  the 

powder.  In  this  position,  the  projectile  was  struck  two 
or  three  times  with  the  ramrod,  which  expanded  the 
lead  into  the  grooves  of  the  barrel.  To  the  bottom  of 
the  sabot  was  attached  a  piece  of  greased  serge,  which 
served  to  soften  the  residuum  of  the  powder  and  facili- 
tate the  loading.  By  this  plan  the  accuracy  of  the 
round  projectile  was  increased,  but  its  range  was  di- 
minished. 

Elongated  projectile.  In  1742,  Robins  pointed  out 
the  superiority  of  the  oval,  or  elongated  form  of  projec- 
tile, and  since  this  many  attempts  have  been  made  to 
employ  it  in  rifled  arms,  especially  in  this  country,  but 
it  remained  for  M.  Delvigne,  followed  by  MM.  Thouve- 
nin  and  Minie,  of  the  French  service,  to  apply  it  suc- 
cessfully to  the  military  service. 

The  form  of  projectile  proposed  by  these  officers  was 
composed  of  a  cylinder  and  conoid.  The  cylinder 
served  as  the  base  of  the  projectile,  and  gave  it  stability 
in  the  bore  of  the  piece;  the  conoidal  surface,  which 
formed  the  point,  was  well  adapted  to  diminish  the 
effect  of  the  air,  by  increasing  the  penetrating  power  of 
the  projectile.     A  single  groove  was  formed  around  the 


310  SMALL-ARMS. PROJECTILES. 

cylinder,  to  contain  a  greased  woollen  thread,  in  place 
of  the  woollen  patch  of  Delvigne. 

It  was  shown  by  the  trials  which  followed,  that  the 
presence  of  this  groove  improved  the  accuracy  of  the 
projectile — a  fact  which  gave  a  new  turn  to  the  inves- 
tigations, and ,  led  to  the  adoption  of  two  additional 
grooves.  The  theory  advanced  in  explanation  of  the 
action  of  these  grooves  was,  that  they  oppose  a  resist- 
ance to  the  air,  which,  acting  on  the  rear  portion  of  the 
projectile,  tends  to  keep  the  point  foremost  in  flight, 
thereby  rendering  the  resistance  of  the  air  uniform,  and 
at  the  same  time  a  minimum. 

The  correctness  of  this  theory  may  be  well  questioned ; 
but  that  the  grooves  exert  a  beneficial  effect,  by  dimin- 
ishing adhesion  to  the  surface  of  the  bore,  and  by  facili- 
tating expansion,  can  scarcely  admit  of  a  doubt. 

282.  Tige,  or  spindle.  Colonel  Thouvenin  proposed 
to  replace  the  chamber  of  Delvigne  by  a  spindle  of 
iron,  screwed  into  the  centre  of  the  breech-screw  (see  a, 

fig.  101).  This  was  found 
to  be  an  excellent  point 


of  support  for  the  base 
of  the   elongated   bullet 
when  forced  by  the  blows 
Fie- 10L  of  the  ramrod.     The  ex- 

pansion of  the  lead  into  the  grooves  secured  the  bullet 
in  place,  and  protected  the  powder  from  moisture. 

Considerable  difficulty,  however,  was  experienced  in 
cleaning  the  space  around  the  spindle;  and,  like  all 
plans  of  forcing  by  the  ramrod,  it  is  subject  to  variation, 
arising  from  the  particular  care  and  strength  exercised 
by  the  soldier. 


BY    THE   POWDER. 


311 


Fig.  102. 


283.  By  form  of  projectile.  This  method  of  forcing  is 
illustrated  in  the  Whitworth  rifle.  The  form  of  the 
bore,  as  in  the  cannon,  is  a  twisted  hexagonal  prism, 
making  a  complete  turn  in  20  inches.     The  projectile 

(fig.  102)  is  made  nearly  of  the  exact  form  and 
size  of  the  bore,  and  is  about  three  diameters 
in  length.  To  prevent  disfiguration  and  strip- 
ping*  which  are  very  liable  to  occur  in  bul- 
lets of  this  length,  fired  with  high  velocities, 
the  lead  is  hardened  by  alloying  it  with  tin 
and  manganese;  and  to  obviate  fouling,  a 
greased  wad  is  placed  between  the  powder 
and  bullet.  As  might  be  expected  from  the  length 
of  the  bullet,  the  amount  of  twist,  and  the  extreme  ac- 
curacy with  which  the  bullet  fits  the  bore,  the  results 
obtained  with  this  arm  are  much  superior  to  those  ob- 
tained with  service-arms. 

284.  By  the  powder.  It  appears  that  the  first  attempt 
to  force  a  projectile  by  the  action  of  the  powder  was 
made  by  Mr.  Greener,  an  English  gunsmith,  in  1836. 
The  plan  which  he  tried  consisted  in  forming  a  cavity 
at  the  base  of  an  oblong  bullet,  and  partially  inserting 
in  it  a  conical  pewter  wedge,  which  was  driven  in  by 
the  force  of  the  powder  in  such  manner  as  to  expand  the 
outer  part  of  the  bullet  into  the  grooves  of  the  barrel. 

Some  years  after  this,  Colonel  Minie  pro- 
duced a  projectile  constructed  on  the  same 
principle,  but  instead  of  a  solid  wedge,  he 
used  a  cup  of  sheet  iron,  which  was  inserted 
into  a  conical  cavity  (fig.  103)  at  the  base 


Fig.  103. 


*  Stripping  is  the  tearing  away  of  the  metal  when  the  projectile  passes  out  of 
the  bore  without  following  the  grooves. 


312  SMALL- ARMS. PROJECTILES. 

of  the  bullet.  The  point  of  the  ball  was  cut  off  to 
prevent  disfiguration  by  the  flat  head  of  the  ramrod. 
This  projectile,  when  fired  from  a  rifle  of  service  calibre, 
generally  possessed  great  range  and  accuracy ;  but  it  had 
certain  defects  which  prevented  it  from  being  exten- 
sively used  in  military  service,  viz. :  it  was  compound  in 
its  structure ;  the  cup  was  sometimes  forced  in  obliquely, 
producing  unequal  expansion;  and,  from  the  large  size 
of  the  cavity,  the  top  was  occasionally  blown  off,  leaving 
the  cylindrical  portion  adhering  to  the  sides  of  the  bore. 

285.  Present  methods.  Not  long  after  the  introduc- 
tion of  the  .Minie  bullet,  it  was  discovered  that,  by  giv- 
ing a  suitable  size  and  shape  to  the  cavity,  the  wedge 
could  be  dispensed  with.  The  projectile  thus  obtained 
was  simple  in  its  structure,  and  gave  better  and  more 
reliable  results  than  the  one  from  which  it  was  derived. 

The  particular  form  and  mode  of  expanding  bullets, 
varies  in  most  military  services ;  in  general  terms,  how- 
ever, all  modern  small-arm  projectiles  are  cylindro-con- 
oidal  in  shape,  and  a  majority  of  them  are  forced  by  the 
action  of  the  powder.  The  effect  of  the  powder  may 
be  direct,  as  in  the  case  where  it  acts  in  the  cavity  of 
a  bullet;  or  it  may  be  indirect,  as  when  it  compresses 
the  bullet  lengthwise,  or,  technically,  "upsets"  it. 

286:   United  states.    The  bullet  used  in  the  United 
States  service,  is  derived  from  that  of 
the  carabine  a  tige,  chiefly,  by  making     /  v\ 
a  conical  cavity  in  its  base.     (See  ^g.    I  \ 

104.)     The  shape  of  the  first  cavity   [    ~~**~— .JL  ^ 
employed,  was  that  of   a  frustum  of    e     /\    \ 
a  cone;  but  this  was  found  defective   C/       \) 
when  used  in  the  rifle-musket,   inas-  Fig.  104. 


313 

much  as  it  rendered  the  bullet  too  weak  at  the  juncture 
of  the  two  exterior  surfaces.  For  arms  with  reduced 
charges  of  powder,  as  in  the  carbine  and  pistol,  the 
large  cavity  is  most  suitable. 

A  description  of  the  musket-bullet  has  been  given  in 
chapter  II.  A  distinguishing  feature  of  this  bullet  is, 
that  no  patch  of  any  kind  is  used  in  loading ;  in  nearly 
all  other  modern  bullets  a  greased  patch  of  cloth,  or 
paper,  envelops  them  when  placed  in  the  bore. 

287.  England.  The  British  bullet  (sometimes  known 
as  the  Pritchett  bullet)  has  a  perfectly  smooth  exterior, 
(fig.  105.)  A  conical  plug  of  box- wood  is 
inserted  into  the  opening  of  the  cavity,  it  is 
said,  more  for  the  purpose  of  preserving  the 
form  of  the  bullet  in  transportation  than 
aiding  in  the  expansion.  The  diameter  and 
weight  of  this  bullet  are  nearly  the  same  as 
in  the  United  States  bullet.  Fig.  105. 

288.  France.  Two  distinct  bullets  are  employed 
in  the  French  army.  The  first  is  shown  in  fig.  101  ; 
it  is  heavy,  and  is  intended  to  have  great  force  and 
accuracy  at  long  distances.  It  is  used  by  troops 
armed  with  the  carabine  a  tige,  as  the  Chas- 
seurs and  Zouaves.  The  second  bullet  is 
shown  in  Hg.  106  ;  it  is  light,  and  without 
much  accuracy,  describes  a  flattened  trajec- 
tory, which  increases  the  chances  of  hitting 
a  line  of  men  at  the  usual  fighting  distance,  fl*  106. 
This  bullet  is  used  by  troops  of  the  line,  who  are  not 
supposed  to  be  skilful  marksmen. 

289.  Austria.  The  Austrian  bullet  belongs  to  the 
class  of  solid  expanding  projectiles.     In  this  particular 


314  SMALL-ARMS. CHARGE    OF    POWDER. 

case,  expansion  is  effected  by  the  crowding  tip   of  the 
disks,   formed  by  cutting   two  deep  grooves 
around  the  cylinder.     (Fig.  107.)     A  portion 
of  the  Austrian   rifles  (those  carried  by  the 
non-commissioned  officers,   and   men   of    the 
third  rank,  who  act  as  skirmishers)  have  a 
spindle  attached  to  the  breech-screw ;  the  ob- 
ject of  which  is,  not  to  aid  in  expanding  the     Flg'  107 
bullet,  but  to  give  it  an  invariable  position  with  reference 
to  the  powder,  and  thereby  secure  uniformity  of  action. 

290.  Switzerland.  Fig.  108  ghows  the  form  of  the 
bullet  used  in  the  Swiss  service.  It  is  solid,  and 
is  forced  by  a  cloth  patch  tied  around  the 
grooves.  The  position  of  the  bullet  with  refer- 
ence to  the  powder  is  constant ;  this  is  deter- 
mined by  a  notch  on  the  ramrod — the  notch 
being  so  arranged  as  to  leave  an  interval  between  Fig.  10a 
the  powder  and  the  bullet. 

The  diameter  of  this  bullet  is  much  less  than  that  of 
any  other  service;  and,  in  consequence  of  its  lightness, 
it  is  fired  with  a  larger  proportional  charge  of  powder. 
Within  the  usual  range  of  small  arms,  it  is  said  to  have 
a  flatter  trajectory,  and  greater  accuracy,  than  any  other 
small-arm  projectile ;  but  at  extreme  ranges  it  loses  its 
velocity  very  rapidly. 

CHARGE  OF  POWDER. 

291.  Conditions  The  proper  charge  of  powder,  for 
a  small-arm,  depends  on  the  calibre,  windage,  length  of 
barrel,  weight  of  the  piece,  and  character  of  the  projec- 
tile.    The  charge  of  the  old  smooth-bored  musket  was 


QUALITIES.  315 

from  one-half  to  one-third  the  weight  of  the  projectile ; 
this  was  necessary  to  make  up  for  the  loss  of  force  by 
great  windage,  and  to  give  the  round  bullet  the  neces- 
sary momentum.  When  the  elongated  bullet  was  in- 
troduced, it  became  necessary  to  reduce  the  charge  to 
prevent  too  severe  recoil ;  besides,  the  mass  of  the  bullet 
being  increased,  a  diminished  velocity  sufficed  to  pro- 
duce the  same  effect. 

In  the  case  of  expanding  bullets,  too  small  a  charge 
will  be  insufficient  to  force  the  lead  into  the  grooves  of 
the  barrel ;  at  the  same  time,  it  is  shown  by  experience 
that,  if  the  charge  be  increased  beyond  a  certain  point, 
the  bullet  is  liable  to  be  disfigured  by  upsetting,  and  its 
accuracy  is  diminished.  TJie  proper  charge  for  elongated 
expanding  bullets  varies  from  one-tenth  to  one-seventh 
the  weight  of  the  projectile. 


LUBRICANT. 

292.  Necessity.  After  a  fire-arm  has  been  discharged 
several  times,  the  residuum  of  the  burnt  powder  collects 
on  the  surface  of  the  bore,  forming  a  hard  substance 
which  seriously  obstructs  loading ;  and  unless  the 
windage  be  very  great,  it  becomes  necessary  to  wipe 
out  the  bore,  or  apply  some  lubricating  substance  to  the 
projectile. 

293.  equalities.  A  proper  lubricating  substance  for 
small-arms  should  be  unaffected  by  changes  of  climate ; 
i.  e.,  it  should  not  be  melted  by  hot,  nor  rendered  too 
hard  by  cold,  weather ;  it  should  not  corrode  the  projec- 
tile, nor  weaken  the  paper  of  the  cartridge,  even  when 


316  DIFFERENT   KINDS    OF    SMALL- ARMS. 

kept  in  store  (as  all  ammunition  is  liable  to  be)  for  a 
considerable  length  of  time. 

294.  Methods*.  The  insertion  of  a  few  drops  of  water, 
or  oil,  in  the  bore,  has  been  tried  with  some  success,  but 
the  most  common  lubricating  substance  is  beeswax,  or 
beeswax  and  tallow,  applied  to  the  projectile,  or  its 
patch.  Beeswax  answers  well  in  a  hot  climate,  and,  if 
it  be  free  from  acid,  does  not  act  on  the  bullet,  nor  the 
patch;  tallow  alone  lubricates  the  bore  well  in  all 
climates,  but  it  corrodes  the  lead  of  the  projectile,  and, 
in  the  course  of  time,  dries  away. 

The  proportion  used  in  the  United  States  service  is 
four  of  beeswax  to  one  of  tallow,  applied  by  dipping 
the  bullet  into  the  melted  substance,  and  immediately 
withdrawing  to  cool.  The  bullet  should  be  previously 
wrarmed,  to  prevent  the  substance  from  peeling  off  by 
too  rapid  cooling.  The  rifle-musket  can  be  thus  fired 
200  times,  at  least,  without  inconvenience. 

DIFFERENT  KINDS  OF  SMALI^ARMS. 

The  small-arms  of  the  United  States  service  are  the 
rifle-musket,  rifle,  carbine,  &n&  pistol. 

295.  Rifle-mu§ket.  The  present  rifle-musket  was 
adopted  in  1855,  with  a  view  of  combining  in  one  piece 
the  range  and  accuracy  of  the  rifle  with  the  advantages 
of  the  musket,  as  regards  lightness,  quickness  of  loading, 
and  facility  of  handling  as  a  pike.  It  is,  therefore,  the 
appropriate  arm  of  troops  acting  on  foot,  and  in  line. 

Length  of  barrel,  .  .  .  40.00  in. 
Length  of  arm  with  bayonet,  .  .74.00  in. 
Weight  of  barrel,        .         .         .  4.25  lbs. 


CARBINE.  317 

Weight  of  arm  complete,         .  .      9.90  lbs. 
Weight  of  projectile,  .         .         .       550.00  grs. 

Weight  of  powder,  .         .  .    60.00  grs. 

Initial  velocity,    ....       960.00  feet. 

The  cadet-musket  only  differs  from  the  foregoing  in 
the  length  of  its  barrel  and  bayonet — the  former  being 
38  in.,  and  the  latter  16  in.  It  would  make  a  suitable 
arm  for  light  troops. 

296.  Rifle.  The  rifle  differs  from  the  rifle-musket  in 
having  a  shorter  and  stouter  barrel,  a  sword-bayonet, 
in  the  mountings,  which  are  made  of  brass  instead  of 
iron,  and  in  having  its  barrel  browned. 

Length  of  barrel,  .  .  .  33.00  in. 
Length  of  arm  with  bayonet,  .  .  72.00  in. 
Weight  of  barrel,        .         .         .  4.80  lbs. 

Weight  of  arm  complete,         .         .     13.00  lbs. 
Charge  (projectile  and  powder),  same 

as  in  rifle-musket. 
Initial  velocity,         ....  910.00  feet. 

297.  Carbine.  The  term  carbine  is  applied  to  an  arm 
used  by  mounted  troops,  and  intermediate  in  weight 
and  length  between  the  rifle  and  pistol.  Both  breech 
and  muzzle  loading  carbines  are  employed,  but  the 
former  are  generally  preferred.  The  ramrod  of  the 
muzzle-loading  carbine  is  attached  to  the  barrel  by  a 
swivel,  which  permits  it  to  be  handled  freely,  but  at  the 
same  time  prevents  it  from  falling  to  the  ground.  The 
carbine  is  secured  to  the  person  of  the  soldier  by  a 
sling,  which  hooks  on  to  a  ring,  moving  on  a  swivel- 
bar  attached  to  the  left  side  of  the  carbine,  thereby 
affording  a  play  to  the  piece  in  loading  and  firing. 


318  DIFFERENT   KINDS    OF    SMALL-ARMS. 

Length  of  barrel,         .         .         .         21.00  in. 

Weight  of  piece,     .         .         .  .       7.50  lbs. 
Weight  of  projectile,  .         .         .       450.00  grs. 

Weight  of  powder,  .         .  .     55.00  grs. 

Initial  velocity,  ....       820.00  feet. 

298.  Pi§toi-cari>ine.  The  pistol-carbine  is  a  muzzle- 
loading  pistol,  with  a  false  butt,  which  permits  it  to  be 
used  either  as  a  pistol  or  carbine.  It  is  particularly 
suited  to  the  service  of  light  artillery. 

Length  of  barrel,         .         .         .         12.00  in. 
Weight  complete,    ....       5.00  lbs. 
Weight  of  projectile,  .         .         .       450.00  grs. 
Weight  of  powder,  .         .         .    40.00  grs. 

Initial  velocity,    ....       603.00  feet. 

299.  Coit'§  pi§toi.  Colt's  pistol  is  constructed  on  the 
revolving  principle,  and  is  composed  of  a  cylinder  (con- 
taining six  charges),  a  rifled  barrel,  and  a  handle  or 
stock.  By  cocking  the  hammer,  the  cylinder  is  made  to 
rotate  around  a  spindle  in  such  a  way  that  a  new  charge 
is  presented  to  the  breech  of  the  barrel  every  time  the 
piece  is  cocked.  The  principal  defects  of  revolving  pis- 
tols are,  that  more  than  one  charge  is  liable  to  go  off  at 
a  time ;  that  the  fragments  of  the  cap  are  liable  to  clog 
the  cylinder ;  and  that  there  is  an  escape  of  gas  through 
the  opening  in  front  of  the  cylinder. 

The  advantage  is  rapidity  of  fire  for  six  discharges. 
Colt's  pistol  is  considered  a  very  reliable  weapon,  par- 
ticularly in  partisan  warfare. 

Length  of  bore  (navy),   .         .         .     9.00  in. 

Weight  of  do 2.40  lbs. 

Weight  of  projectile,       .         .         125.00  grs. 


SPORTING    RIFLE.  319 

Weight  of  powder,     .         .         .        14.00  grs. 
Initial  velocity,         .         .         .         760.00  feet. 

300.  Sporting  rifle.  American  sporting  rifles  have 
long  enjoyed  a  reputation  for  extreme  accuracy  of  fire. 
This  has  been  attained  by  introducing  into  their  con- 
struction many  refinements  which,  though  ingenious 
and  effective,  are  incompatible  with  the  strength,  safety, 
and  rapidity  of  fire  of  a  military  arm.  To  give  stiff- 
ness and  steadiness  to  the  barrel,  it  is  made  very  heavy 
in  proportion  to  the  charge ;  to  prevent  the  bullet  from 
being  disfigured  by  a  heavy  proportional  charge  of 
powder,  the  calibre  is  made  as  small  as  the  range  will 
permit ;  to  render  friction  in  the  bore  uniform,  the  sur- 
face is  carefully  wiped  after  each  discharge ;  to  prevent 
disfiguring  the  corners  of  the  muzzle,  the  bullet  is  in- 
serted into  the  bore  through  a  false  muzzle ;  to  centre 
the  bullet  properly  in  the  bore,  it  is  started  with  an  in- 
strument called  the  straight  starter;  and,  finally,  the 
piece  is  aimed  with  a  globe,  or  telescopic  sight,  and 
fired  with  a  hair-trigger. 

The  dimensions,  &c,  of  a  James's  rifle,  of  this  class, 
belonging  to  the  museum  of  the  Academy,  are  as  fol- 
lows, viz.: 

Length  of  barrel,       ....       32.50  in. 

Weight  of    do 16.50  lbs. 

Calibre,  00.45  in. 

Weight  of  bullet,  .         .         -  217.00  grs. 

Weight  of  powder,  ....       100.00  grs. 

Initial  velocity,     ....        1,900.00  feet. 


320  MANUFACTURE   OF    SMALL- ARMS. 


MANUFACTURE  OF  SMALL-ARMS. 

301.  Where  made.  With  the  exception  of  swords 
and  patent-arms,  all  small-arms  for  the  United  States 
army  and  militia  are  made  at  the  national  armories, 
situated  at  Springfield,  Mass.,  and  Harper's  Ferry,*  Ya. 
These  armories  are  under  the  general  charge  of  the 
chief  of  ordnance,  who,  by  the  authority  of  the  war 
department,  furnishes  the  models,  and  prescribes  the 
kind  and  quantity  of  work  to  be  done ;  the  operations 
are  conducted  by  civilians. 

302.  How  made.  A  principal  requisite,  in  the  manu- 
facture of  small-arms,  is,  that  similar  parts  of  the  same 
kind  of  arm,  or  model,  shall  be  capable  of  interchange. 
This  demands  a  higher  degree  of  accuracy  in  the  work- 
manship than  can  be  attained  by  hand-labor,  without 
great  cost,  and  the  consequence  is,  that  machinery  is 
now  very  generally  employed  in  this  branch  of  man- 
ufacture. 

303.  Operation**.  The  principal  operations  of  manu- 
facturing arms  are  welding,  swaging,  boring,  turning, 
drilling,  tapping,  milling  1  cutting  and  filing,  grinding, 
case-hardening,  tempering,  Midi  polishing.  Welding  and 
swaging  are  performed  by  blacksmiths ;  the  other  oper- 
ations, by  armorers  or  finishers. 

304.  Welding.  Welding  is  the  process  of  uniting 
certain  metals  by  means  of  heat  and  pressure.  To 
bring  the  heated  substances  into  perfect  contact,  the 
joining  surfaces  should  be  freed  from  the  coating  of 

♦Since  the  first  edition  of  this  work  was  published,  the  Harper's  Ferry  armory 
has  been  destroyed,  and  is  no  longer  used  for  government  purposes. 


ROLLING    BARRELS.  321 

oxide  which  generally  covers  them ;  and  this  is  done  by 
applying  a  composition  of  ten  parts  of  borax  to  one  of 
sal-ammoniac. 

The  most  important  welds  in  the  musket  are  those 
of  the  barrel,  and  the  blade  and  socket  of  the  bayonet. 
The  first  was  formerly  done  under  the  trip-hammer; 
it  is  now  better  and  more  economically  performed  by 
rollers. 

305.  Roiling  barrels.  The  material  from  which  a 
musket-barrel  is  made  is  a  flat  bar  of  wrought  iron,  14 
inches  long,  5|  inches  wide,  and  T9T  inches  thick;  the 
edges  are  bevelled  so  that  they  will  make  a  perfect  lap- 
joint  when  united  as  a  tube.  The  several  processes  of 
welding  are  curving,  welding,  and  straightening. 

Curving.  The  plate  is  heated  in  a  reverberatory  fur- 
nace, to  a  red  heat,  and  then  passed  between  the  grooves 
of  the  curving-rolls  (fig.  109),  to  bring  the  bevelled  edges 

in  contact.  There  are  five 
grooves,  two   being  open 


grooves,   and   three   have 
tongues  upon  the   upper 
Fig.  109.  roll    to    bend    the    plate 

down  into  the  lower  groove.  The  grooves  also  differ 
in  size.  The  first  one  gives  the  plate  the  shape  of  a 
trough;  the  second  and  third  gradually  contract  it, 
without  changing  its  form;  the  fourth  and  fifth  are  par- 
allel grooves,  which  bring  the  edges  of  the  plate  in  con- 
tact. The  object  of  so  many  grooves  is,  to  bend  the  plate 
gradually,  and  prevent  it  from  being  split  open,  in  case 
the  iron  is  brittle.  In  this  way,  450  plates  can  be  bent 
by  one  set  of  rolls  in  a  day. 

Welding.     The  plates  thus  bent,  or  "  cylinders"  are 

21 


322  MANUFACTUKE   OF    SMALL-AEMS. 

replaced  in  the  furnace  to  prepare  them  for  the  weld- 
ing-rolls. The  workmen  are  supplied  with  eight  steel 
mandrels,  or  rods  terminated  at  the  point  with  an  egg- 
shaped  bulb;  the  bulbs  vary  from  .71  in.  to  .46  in.  in 
diameter.  When  one  of  the  cylinders  is  brought  to  a 
white,  or  welding  heat,  a  workman  thrusts  the  largest 
mandrel  through  it,  whilst  it  is  in  the  furnace.  He 
then  carries  it  to  the  rolls  (only  one  of  which  is  shown 
in  fig.  110),  and  placing  the  mandrel  through  the  frame, 
he  introduces  the  end  of  the  cylinder  into  the  first 
groove;  the  action  of  the  rolls  is  to  slip  the  cylinder 
over  the  mandrel,  the  centre  of  the  bulb  being  placed 

and  held  in  the  plane 


of  the  axis  of  the  two 
rolls.  The  cylinder  is 
then  straightened  by 
striking  it  on  a  flat 
iron  table,  and  placed 
Fi&-  uo  in  the  furnace  to  be 

reheated.  The  second  size  mandrel  is  then  inserted,  and 
the  cylinder  is  passed  through  the  second  groove  in  the 
rolls,  which  is  smaller  than  the  first,  and  the  welding  is 
completed. 

The  object  of  the  remaining  grooves  is,  to  give  the 
proper  form,  or  taper,  to  the  cylinder,  and  for  this  pur- 
pose they  are  made  of  the  same  shape  as  the  required 
barrel.  As  each  groove  makes  a  single  circuit  of  the 
rolls,  and  as  the  rolls  are  continually  in  motion,  it  re- 
quires some  dexterity  on  the  part  of  the  workman  to 
insert  the  end  of  the  cylinder  at  the  right  moment. 

In  this  way  the  cylinder  is  passed,  breech  foremost, 
through  five  of  the  taper  grooves;    it  is  then  passed 


DRILLING    AND    TAPPING.  323 

twice  through  the  last  groove,  without  a  mandrel,  to 
make  it  smooth. 

In  passing  through  each  taper  groove,  the  barrel  is 
reheated  (to  a  red  heat),  as  the  bulb  of  the  mandrel 
chills  the  interior  surface. 

Straightening.  The  welding  process  being  completed, 
a  workman  places  the  barrel  in  the  straightening  ma- 
chine, which  is  composed  of  two  dies,  each  of  the  length 
and  shape  of  the  half-barrel,  and  which  close  upon  each 
other  as  the  workman  turns  the  barrel  around  its  axis 
with  a  pair  of  tongs. 

In  this  way  about  75  barrels  can  be  finished  by  one 
set  of  workmen  in  a  day. 

306.  Swaging.  Swaging  is  the  operation  by  which 
the  rough  iron  or  steel  is  converted  into  a  piece  of  suit- 
able size  and  shape  for  the  finisher.  It  is  done  by  forc- 
ing the  piece  of  heated  metal  into  a  die  by  means  of  a 
heavy  drop-weight ;  the  machine  is  called  a  drop-hammer. 

307.  Boring.  Boring  is  the  operation  of  forming  the 
bore  of  the  barrel.  The  manner  of  performing  it,  and 
the  character  of  the  tools  used,  depend  on  the  metal 
employed.  If  it  be  steel,  the  piece  to  be  bored  is  formed 
into  a  solid  bar,  of  homogeneous  texture ;  if  of  wrought 
iron,  it  is  formed  into  a  tube,  some  portions  of  which 
are  liable  to  be  harder  and  more  difficult  to  cut  than 
others.  In  the  first  case,  a  stationary  drill  is  driven 
through  the  piece  which  revolves ;  in  the  second  case, 
the  boring  instrument  revolves  rapidly,  and,  at  the  same 
time,  is  drawn  through  the  hole  left  by  the  welding 
mandrel. 

308.  Drilling  and  tapping.  The  object  of  drilling  is 
to  form  holes  for  the  screws,  rivets,  &c. ;  and  that   of 


324  SMALL-ARMS. MANUFACTURE    OF. 

tapping,  is  to  convert  the  surface  of  the  hole  into  a  fe- 
male screw.  The  former  operation  is  performed  by  the 
drill-press ;  the  latter  by  an  instrument  called  a  tap, 
which  is  made  of  a  piece  of  steel,  of  a  pyramidal  form, 
and  on  the  edges  of  which  are  segments  of  screw 
threads.  In  all  operations  of  cutting  and  drilling 
wrought  iron,  it  is  necessary  to  use  oil  or  water  to  pre- 
serve the  temper  of  the  tools.  In  working  cast  iron,  no 
cooling  substance  is  required. 

309.  Turning.  The  object  of  turning  is  to  give  shape 
and  smoothness  to  the  exterior  of  a  body,  and  is  accom- 
plished in  a  machine  called  a  lathe.  The  body  is  gen- 
erally made  to  revolve  around  a  fixed  axis,  and  a  cut- 
ter, which  has  a  motion  parallel  to  this  axis,  is  made  to 
press  against  its  surface ;  the  combination  of  these  two 
motions  cuts  away  a  spiral  chip,  and  leaves  a  new  sur- 
face concentric  with  the  axis.  It  will  be  easily  seen 
that  if  the  cutter  has,  in  addition  to  its  motion  parallel 
to  the  axis  of  rotation,  another  perpendicular  to  it,  that 
the  resulting  figure  will  be  no  longer  round,  but  irregular. 

This  constitutes  the  principle  of  eccentric  turning,  and 
affords  the  means  of  turning  an  almost  infinite  variety 
of  shapes,  simply  by  regulating  the  motion  of  the  cutter 
by  a  pattern,  or  model  of  hardened  steel.  In  this  way 
gun-stocks,  and  other  irregular  figures,  are  formed  by 
machinery ;  the  principle  has  even  been  used  in  copying 
statuary. 

310.  Milling.  Pieces  of  metal  which  are  not  suited 
to  the  turning-lathe,  may  be  reduced  to  their  proper 
shape  by  milling,  an  operation  adapted  to  nearly  all 
surfaces  which  have  rio*ht-line  elements. 

It  is  performed  by  a  revolving  cutter,  armed  with 


CASE-HARDENING.  325 

saw-teeth,  while  the  piece  to  be  cut  is  fastened  on  a 
carriage,  which  moves  steadily  under  the  cutter,  and 
along  a  plane  director. 

The  shape  of  the  cut  surface  depends  on  the  shape 
of  the  profile  of  the  cutter ;  for  instance,  to  dress  the 
sides  of  a  lock-plate,  a  cylindrical  cutter  would  be  used ; 
to  trim  the  edges,  a  curved  one.  By  combining  differ- 
ent shaped  cutters  on  the  same  arbor,  or  shaft,  a  great 
variety  of  surfaces  can  be  formed. 

311.  Cutting  and  filing.  Cutting  and  filing  are  done 
by  the  hand — the  former  with  a  cold-chisel,  and  the 
latter  by  a  file.  They  are  employed  to  finish  such  parts 
as  are  not  well  adapted  to  machinery.  To  guide  the 
workman  in  giving  the  proper  form,  the  piece  is  placed 
in  a  hardened  steel  frame,  called  ajeg. 

312.  Qrinding  and  polishing.  Grinding  is  done  with 
rapidly-revolving  grindstones,  and  is  principally  con- 
fined to  finishing  the  bayonet,  and  exterior  of  the 
barrel.  Polishing  the  surface  of  finished  parts  is  done 
with  emery-wheels,  which  revolve  with  great  rapidity. 
The  wheels  are  made  of  wood,  and  the  circumference 
is  covered  with  buff  leather,  to  which  is  glued  a  coat- 
ing of  emery. 

313.  Case-hardening.  Case-hardening  is  the  conver- 
sion of  the  surface  of  wrought  iron  into  steel,  to  enable 
it  to  receive  a  polish,  or  bear  friction.  The  process  con- 
sists in  heating  the  iron  to  a  cherry  red,  in  a  close  vessel, 
in  contact  with  carbonaceous  matter,  and  then  plunging 
it  into  cold  water.  Old  shoes  are  generally  employed 
for  this  purpose  at  the  armories,  although  bones,  hoofs, 
soot,  &c,  will  answer.  The  materials  should  be  first 
burnt,  and  then  pulverized. 


326  SMALL- ARMS. MANUFACTURE    OF. 

314.  Hardening  and  tempering  steel.  Hardening  is 
effected  by  heating  the  steel  to  a  cherry  red,  or  until 
the  scales  of  oxide  are  loosened  on  its  surface,  and 
plunging  it  into  a  liquid,  as  water,  oil,  &c.,  or  placing 
it  in  contact  with  some  cooling  solid;  the  degree  of 
hardness  depends  on  the  heat,  and  the  rapidity  of 
cooling.  Steel  is  thus  rendered  so  hard  as  to  resist 
the  hardest  file;  and  it  becomes  at  the  same  time  ex- 
tremely brittle. 

Tempering.  In  its  hardest  state  steel  is  too  brittle 
for  most  purposes;  the  requisite  strength  and  elasticity 
are  obtained  by  tempering,  which  is  done  by  heating 
the  hardened  steel  to  a  certain  degree,  and  juunging  it 
into  cold  water. 

The  requisite  heat  is  usually  ascertained  by  the  color 
which  the  surface  of  the  steel  presents,  due  to  the  film 
of  oxide  formed  on  it : 

At  450°  Fahr.,  a  pale  j  Suitable  for  hard  instruments, 

straw  color.  {      as  the  faces  of  hammers,  &c. 

f  Gives  a  spring  temper,  or  one 

At  600°  Fahr.,  a  grey- J       that  will  bend  before  break- 

ish  blue.  j       ing :  suitable  for  saws,  sword- 

v     blades,  &c. 

Shades  of  colors  between  these  extremes,  give  inter- 
mediate degrees  of  hardness.  If  steel  be  heated  above 
(300°,  the  effect  of  the  hardening  process  is  destroyed. 
The  parts  of  small  arms  are  tempered  by  dipping  them 
in  oil,  then  heating  them  until  the  oil  is  burned  off, 
when  they  are  again  plunged  into  cold  water. 

315.  Blueing.  A  blue  color  may  be  given  to  the 
surface  of  iron  and  steel  parts,  by  subjecting  them  to  a 


OBJECT    OF   INSPECTION.  327 

certain  degree  of  heat.  As  soon  as  the  proper  shade 
of  blue  makes  its  appearance,  the  piece  is  removed  and 
allowed  to  cool,  when  the  color  becomes  fast. 

316.  Browning.  Browning  is  the  coating  given  to 
a  gun-barrel  to  protect  it  from  the  action  of  the  at- 
mosphere, and  to  prevent  the  surface  from  reflecting  the 
sunlight. 

The  process  consists  in  forming  a  coat  of  rust,  with 
a  mixture  of  such  materials  as  spirits  of  wine,  blue 
vitriol,  tincture  of  steel,  nitric  acid,  &c.  (see  Ord.  Manl.), 
on  the  clean  surface  of  the  barrel,  and  then  rubbing  it 
well  with  a  steel  scratch-card  until  it  has  a  metallic  lus- 
tre. This  operation  is  repeated  about  a  dozen  times, 
until  the  coating  has  a  deep  brown  color.  The  barrel 
is  then  washed  with  boiling  water,  to  dissolve  away  any 
of  the  corroding  mixture  that  may  remain,  and,  when 
cold,  is  covered  with  sperm  oil. 

When  the  browning  has  been  worn  away  in  places, 
it  may  be  entirely  removed — first,  by  boiling  in  lime- 
water,  to  remove  the  varnish  or  grease,  and  then  soak- 
ing in  vinegar,  which  loosens  the  browning  so  that  it 
can  be  wiped  away  with  a  rag. 


INSPECTION  OF  SMALL-AKMS. 

317.  Object.  The  objects  of  inspecting  small-arms 
are,  to  verify  the  dimensions,  the  workmanship,  and  the 
quality  of  the  materials  of  the  various  parts. 

Inspections  at  the  armories  are  made  by  the  foremen 
of  the  several  departments  of  work,  under  the  direc- 
tion of  the  master  armorer.      To  secure  uniformity  in 


328  SMALL- ARMS. INSPECTION    OF. 

all  service-arms,  comparative  inspections  are  occasionally 
made  of  the  work  from  the  different  armories ;  the  parts 
of  one  set  are  required  to  interchange  freely  with  those 
of  another.  Partial  inspections  are  made  at  the  dif- 
ferent stages  of  manufacture,  to  prevent  unnecessary 
labor  from  being  expended  on  defective  pieces.  Con- 
tract-arms are  inspected  by  an  officer  of  the  ordnance 
department,  and  by  sworn  assistants  taken  from  one  of 
the  armories. 

The  following  regulations  for  the  inspection  of  fin- 
ished arms,  the  care  and  preservation  of  arms  in  service, 
&c,  are  taken  from  the  Ordnance  Manual. 

318.  Fini§iied  arm.  The  inspector  will  examine  the 
finished  arm  on  every  side,  to  see  that  the  parts  are  well 
fitted  together ;  he  will  also  verify  the  principal  dimen- 
sions and  forms,  by  means  of  appropriate  gauges  and 
patterns. 

319.  Barrel.  The  diameter  of  the  bore  should  be 
verified  with  the  standard  and  limit  gauges.  The  stand- 
ard gauge  is  a  cylinder  of  the  diameter  of  the  bore 
(.58  in,),  and  the  limit  gauge  is  .0025  inch  greater. 
The  former  should  pass  freely  through  the  bore,  and  the 
latter  should  not  enter  it.  The  barrel  should  enter  the 
groove  of  the  stock,  one-half  of  its  diameter,  and  should 
bear  uniformly  throughout,  particularly  at  the  breech. 
The  vent  should  be  accurate  in  its  dimension,  position, 
and  direction,  and  a  wire  should  be  passed  through  it, 
to  s'ee  that  it  is  free.  The  cone  should  be  sound.  The 
shoulders  of  the  breech-screw  should  fit  close  to  the  end 
of  the  barrel,  and  it  should  be  free  from  cracks  or  flaws 
about  the  tang-screw  hole.  The  straightness  of  the 
barrel  may  be  ascertained  by  turning  out  the  breech- 


stocks.  329 

screw,  and  holding  the  barrel  up  to  the  light,  and  re- 
flecting the  image  of  a  straight-edge  from  the  surface  of 
the  bore.  If  the  barrel  be  straight,  the  reflected  image 
will  be  straight  in  all  positions  of  the  barrel.  The 
bore  should  be  free  from  hammer-marks,  ring-bores,  cin- 
der-holes, flaws,  cracks,  &c,  and  the  bayonet-stud  and 
sight  notches,  should  not  be  cut  too  deep. 

320.  Ramrod.  The  temper  of  the  ramrod  may  be 
tested  by  springing  it  in  four  directions,  with  the  point 
resting  on  the  floor.  When  the  musket-rod  is  bent 
six  inches  out  of  line,  it  should  spring  back  perfectly 
straight  without  setting.  Its  soundness  may  be  tested 
by  striking  it  with  a  piece  of  metal,  or  by  bending  it 
over  the  edge  of  a  block  of  wood;  in  the  first  case  the 
sound  emitted  should  be  clear,  and  in  the  second  case 
the  flaws  or  cracks  will  be  opened.  The  screw  on  the 
point  of  the  rod  should  be  properly  cut ;  it  should  bear 
properly  in  its  groove,  neither  too  light,  nor  too  loose. 
The  point  should  rest  on  the  stop. 

321.  Bayonet.  The  form  and  dimensions  of  the  bay- 
onet are  verified  with  the  proper  gauges ;  the  temper 
is  tried  by  resting  the  point  against  the  floor,  and  spring- 
ing the  blade  smartly  in  four  directions — toward  the 
back,  face,  and  two  edges — grasping  the  butt  of  the 
stock  with  the  right  hand,  and  the  middle  of  the  bar- 
rel with  the  left.  After  this,  inspect  for  cracks  and 
flaws.  To  test  the  welding  of  the  blade  to  the  socket, 
strike  the  elbow  smartly  on  the  work-bench. 

322.  stock§.  The  wood  should  be  straight-grained, 
well-seasoned,  and  free  from  sap  and  worm-holes.  The 
effect  of  unseasoned  wood  will  be  to  rust  the  lock  and 
barrel.     It  may  be  detected  by  the  odor  of  a  fresh  cut, 


330  SMALL-ARMS. PACKAGE    AND    STORAGE    OF. 

or  by  the  crumbling  of  a  chip  when  pressed  in  the  fin- 
gers. The  edges  should  be  sharp  and  clear,  and  free 
from  splits.  The  dimensions,  which  concern  the  fitting 
of  the  parts,  should  be  carefully  verified. 

323.  l.ock.  All  parts  of  the  lock  should  be  sound, 
well  filed,  and  of  proper  form  and-  dimensions.  The 
temper  of  the  hardened  parts  should  be  tried  with  a 
fine-cut  file.  See  that  the  main  and  sear  springs  have 
the  requisite  power. 

Examine  carefullv  the  action  of  the  lock;  see  that 
the  movable  parts  are  free,  i.e.,  do  not  rub  against  other 
parts  when  in  motion.  Snap  on  the  cone,  and  see  that 
it  fits  its  seat  properly.  Let  the  hammer  down  several 
times,  to  judge  of  the  working  of  the  parts.  See  that 
the  interior  parts  are  not  wood-bound ;  that  it  does  not 
go  off  at  half-cock  when  the  trigger  is  pulled  hard,  and 
that  it  goes  neither  too  hard  nor  too  easy  when  cocked. 

324.  mountings  The  trigger  should  work  freely,  but 
should  have  no  lateral  motion  in  the  guard-plate.  The 
guard-plate  should  not  be  screwed  up  too  hard,  lest  the 
trigger  be  brought  too  close  to  the  sear.  The  bands 
should  be  close  to  the  stock,  but  not  so  tight  as  to  re- 
quire much  force  to  move  them.  The  band-springs 
should  spring  back  freely  when  pressed  down. 

The  sights  are  aligned  by  the  flats  of  the  barrel,  which 
are  equidistant  from  the  axis  of  the  bore,  by  construc- 
tion. The  alignment  can  only  be  verified  by  firing  at 
a  target. 

« 

PACKING  AND  STORAGE  OF  ARMS. 

325.  Boxes.    Packing-boxes  for  muskets  are  made  of 


STORAGE.  331 

well-seasoned  pine  boards.  Each  box  contains  twenty 
muskets,  in  two  rows  of  ten  each.  The  pieces  are  kept 
from  jostling  and  injuring  each  other  by  grooved  clamps. 
The  bayonets  are  unfixed,  and  placed  securely  on  the 
bottom  of  the  box,  and  the  appendages  are  placed  in  a 
small  apartment  at  the  end. 

When  the  regular  packing-box  cannot  be  had,  arms 
may  be  packed  in  boxes  with  straw  that  is  dry  and  free 
from  dust,  by  forming  it  into  a  rope,  and  wrapping  it 
around  them;  hay  will  not  answer.  They  are  then 
placed  in  rows,  the  lower  row  resting  on  three  cushions 
of  .straw  placed  on  the  bottom.  The  butts  are  kept 
apart  by  wedges  of  straw ;  and  the  top  row  is  covered 
with  straw,  pressed  in  by  the  cover,  which  is  fastened 
by  two  hoops. 

326.  storage.  Arms  are  kept  at  the  arsenals  either  in 
the  boxes  in  which  they  are  received  from  the  armories, 
or  in  racks. 

Each  kind  is  kept  separate,  and  arranged  according 
to  model,  the  place  and  year  of  construction,  and  the 
time  when  they  were  last  cleaned. 

New  arms  are  kept  distinct  from  those  which  have 
been  repaired.  Arms  of  peculiar  kinds,  arms  to  be 
repaired,  and  unserviceable  or  condemned  arms,  are 
kept  separate. 

Limbs  and  spare  parts,  intended  for  repairs  of  arms, 
should  be  kept  in  store  by  themselves,  in  a  dry  place, 
classed  according  to  the  kind  of  arms,  and  to  the  model 
and  year  of  fabrication,  and  labelled  accordingly. 

All  arms  in  store  should  be  frequently  examined,  to 
see  that  they  are  not  rusty.  Those  which  are  rusty 
should  be  immediately  cleaned  and  oiled  with  sperm 


332         SMALL- ARMS. PRESERVATION   AND    CARE    OF. 

oil.  If  browned  arms  are  affected  with  specks  of  rust, 
they  should  be  rubbed  with  linseed  oil ;  and  if  the 
acid  be  not  neutralized,  proper  authority  should  be 
obtained  to  remove  and  renew  the  browning.  Empty 
packing-boxes,  from  which  the  arms  in  racks  are  taken, 
should  be  kept,  with  the  necessary  parts,  in  the  attics, 
or  other  dry  situations.  Storehouses  for  arms  should 
be  aired  in  clear,  dry  weather. 

PRESERVATION  AND  CAEE  OF  ARMS  IN 
SERVICE. 

327.  in§truction.  The  officers,  non-commissioned  offi- 
cers, and  soldiers,  should  be  instructed  and  practised  in 
the  nomenclature  of  the  arms,  and  the  manner  of  dis- 
mounting and  mounting  them,  and  the  precautions  and 
care  required  for  their  preservation. 

Each  soldier  should  have  a  screw-driver  and  a  wiper, 
and  each  non-commissioned  officer  a  wire  tumbler-punch 
and  a  spring-vice.  No  other  implements  should  be 
used  in  taking  arms  apart,  or  in  setting  them  up. 

In  the  inspection  of  arms,  officers  should  attend  to 
the  qualities  essential  to  service,  rather  than  to  a  bright 
polish  on  the  exterior.  Arms  should  be  inspected  in 
the  quarters,  at  least  once  a  month,  with  the  barrel  and 
lock  separated  from  the  stock. 

328.  Dismounting  by  a  soldier.  The  rifle-musket 
should  be  dismounted  in  the  following  order,  viz. : — 1st. 
Unfix  the  bayonet ;  2d.  Insert  the  tompion ;  3d.  Draw 
the  ramrod ;  4th.  Turn  out  the  tang-screw ;  5th.  Take 
off  the  lock ;  to  do  this,  put  the  hammer  at  half-cock, 
and  partially  unscrew  the  side-screws,  then,  with  a  slight 


TO    CLEAN   THE    BARREL.  333 

tap  on  the  head  of  each  screw  with  a  wooden  instru- 
ment, loosen  the  lock  from  its  bed  in  the  stock ;  turn 
out  the  side-screws,  and  remove  the  lock  with  the  left 
hand ;  6th.  Remove  the  side-screws  without  disturbing 
the  washers;  7th.  Take  off  the  bands  in  order,  com- 
mencing with  the  uppermost ;  8th.  Take  out  the  bar- 
rel. In  doing  this,  turn  the  musket  horizontally,  with 
the  barrel  downward,  holding  it  loosely,  with  the  left 
hand  below  the  rear  sight,  and  the  right  hand  grasping 
the  stock  by  the  handle  ;  tap  the  muzzle  on  the  ground, 
if  necessary,  to  loosen  the  breech.  If  an  attempt  were 
made  to  pull  the  barrel  out  by  the  muzzle,  it  would,  in 
case  it  were  wood-bound,  be  liable  to  split  at  the  head 
of  the  stock. 

The  foregoing  parts  of  the  rifle-musket  are  all  that 
should  usually  be  taken  off,  or  dismounted  by  the  sol- 
dier. The  breech-screw  should  be  taken  out  only  by  an 
armorer,  and  never  in  ordinary  cleaning.  The  mount- 
ings, cone,  and  cone-seat  screw,  should  not  be  taken  off, 
nor  should  the  lock  be  taken  apart,  except  by  permis- 
sion of  an  officer. 

329.  To  clean  the  barrel.  1st.  Stop  the  vent  with  a 
peg  of  soft  wood,  or  piece  of  rag  or  soft  leather  pressed 
down  by  the  hammer ;  pour  a  gill  of  water  (warm,  if  it 
can  be  had)  into  the  muzzle ;  let  it  stand  a  short  time, 
to  soften  the  deposit  of  powder;  put  a  plug  of  soft 
wood  into  the  muzzle,  and  shake  the  water  up  and 
down  the  barrel ;  pour  it  out,  and  repeat  the  washing 
until  the  water  comes  out  clear ;  remove  the  peg  from 
the  cone,  and  stand  the  barrel,  muzzle  downward,  to 
drain,  for  a  few  moments. 

2d.  Screw  the  wiper  on  the  end  of  the  ramrod,  and 


334        SMALL-ARMS. PRESERVATION    AND    CARE    OF. 

put  a  piece  of  dry  doth,  or  tow,  round  it,  sufficient  to 
prevent  it  from  chafing  the  grooves  of  the  "barrel ;  wipe 
the  barrel  dry,  changing  the  cloth  two  or  three  times. 

3d.  Put  no  oil  into  the  vent,  as  it  will  clog  the  pas- 
sage, and  cause  the  first  primer  to  miss  fire ;  but,  with 
a  slightly  oiled  rag  on  the  wiper,  rub  the  bore  of  the 
barrel,  and  the  face  of  the  breech-screw,  and  immedi- 
ately insert  the  tompion  into  the  muzzle. 

4th.  To  clean  the  exterior  of  the  barrel,  lay  it  flat  on 
a  bench  or  board,  to  avoid  bending  it.  The  practice  of 
supporting  the  barrel  at  each  end,  and  rubbing  it  with 
a  strap,  buffstiek,  ramrod,  or  any  other  instrument,  to 
burnish  it,  is  pernicious,  and  should  be  strictly  forbidden. 

5th.  After  firing,  the  barrel  should  always  be  washed 
as  soon  as  practicable ;  when  the  water  comes  off  clear, 
wipe  the  barrel  dry,  and  pass  into  it  an  oiled  rag.  Fine 
flour  of  emery  cloth  is  the  best  article  to  clean  the  exte- 
rior of  the  barrel. 

330.  To  clean  the  lock.  Wipe  every  part  with  a 
moist  rag,  and  then  a  dry  one ;  if  any  part  of  the  inte- 
rior shows  rust,  put  a  drop  of  oil  on  the  point  or  end  of 
a  piece  of  soft  wood  dipped  into  flour  of  emery;  rub 
out  the  rust,  and  wipe  the  surface  dry ;  then  rub  every 
part  with  a  slightly  oiled  rag. 

331.  To  clean  the  mountings.  For  iron  and  steel 
parts,  use  fine  emery  moistened  with  oil,  or  emery  cloth. 
For  brass  parts,  use  rotten-stone  moistened  with  vinegar 
or  water,  applied  with  a  rag,  brush,  or  stick;  oil  or 
grease  should  be  avoided.  The  dirt  may  be  removed 
from  the  screw-holes  by  screwing  a  piece  of  soft  wood 
into  them.  Wipe  all  parts  with  a  linen  rag,  and  leave 
the  parts  slightly  oiled. 


lock.  335 

332.  Dismounting  by  an  armorer.  The  parts  which 
are  specially  assigned  to  be  dismounted  by  an  experi- 
enced armorer  will  be  stated  in  their  regular  order,  fol- 
lowing No.  8,  viz. : 

9th.  Unscrew  cone  ;  10th.  Take  out  cone-seat  screw  ; 
11th.  Take  out  band-springs,  using  a  wire  punch  ;  12  th. 
Take  out  the  guard-screws.  Be  careful  that  the  screw- 
driver does  not  slip,  and  mar  the  stock;  13th.  Remove 
the  guard  without  injuring  the  wood  at  either  end  of 
the  plate  ;  14th.  Remove  the  side-screw  washers  with  a 
drift-punch;  15th.  Remove  the  butt-plate;  16th.  Re- 
move the  rear-sight ;  17th.  Turn  out  the  breech-screw 
by  means  of  a  "  breech-screw  wrench"  suited  to  the 
tenon  of  the  screw.  No  other  wrench  should  ever  be 
used  for  this  purpose,  and  the  barrel  should  be  held  in 
clamps,  neatly  fitting  the  breech. 

333.  L.ock.  To  take  the  lock  apart : — 1st.  Cock  the 
piece,  and  apply  the  spring-piece  to  the  mainspring ; 
give  the  thumb-screw  a  turn  sufficient  to  liberate  the 
spring  from  the  swivel  and  mainspring  notch  ;  remove 
the  spring;  2d.  The  sear-spring  screw;  3d.  The  sear- 
screw  and  sear ;  4th.  The  bridle-screw  and  bridle ;  5th. 
The  tumbler-screw;  6th.  The  tumbler.  This  is  driven 
out  with  a  punch,  inserted  in  the  screw-hole,  which  at 
the  same  time  liberates  the  hammer ;  7th.  Detach  the 
mainspring  swivel  from  the  tumbler  with  a  drift -punch; 
8  th.  Take  out  the  feed-finger  and  spring ;  9th.  The  catch- 
spring  and  screw. 

As  a  general  rule,  all  parts  of  the  musket  are  assem- 
bled in  the  inverse  order  in  which  they  are  dismounted. 
Before  replacing  screws,  oil  them  slightly  with  good 
sperm  oil  (inferior  oil  is   converted  into   a  gum  which 


336  SMALL- ARMS. INSPECTION    OF,    ETC. 

clogs  the  operation  of  the  parts).  Screws  should  not  be 
turned  in  so  hard  as  to  make  the  parts  bind.  When  a 
lock  has,  from  any  cause,  become  gummed  with  oil  and 
dirt,  it  may  be  cleaned  by  boiling  in  soap-suds  or  in 
pearlash  or  soda  water ;  heat  should  never  be  applied  in 
any  other  way. 

334.  Precautions  in  using.  In  ordering  arms  on 
parade,  let  the  butt  be  brought  gently  to  the  ground, 
especially  if  the  ground  be  hard.  This  will  save  the 
mechanism  of  the  lock  from  shocks,  which  are  very  in- 
jurious to  it,  and  which  tend  to  loosen  and  mar  the 
screws,  and  split  the  woodwork. 

The  ramrod  should  not  be  "  sprung"  with  unnecessary 
force,  for  fear  of  injuring  the  corners  of  the  grooves ; 
and,  in  stacking  arms,  care  should  be  taken  not  to  in- 
jure the  bayonets  by  forcibly  straining  the  edges  against 
each  other. 

No  cutting,  marking,  or  scraping  the  wood  or  iron 
should  be  allowed ;  and  no  part  of  the  gun  should  be 
touched  with  a  file.  Take  every  possible  care  to  pre- 
vent water  from  getting  between  the  lock,  or  barrel, 
and  stock.  If  any  should  get  there,  dismount  the  gun 
as  soon  as  possible,  clean  and  oil  the  parts  as  directed, 
and  see  that  they  are  perfectly  dry  before  assembling 
them. 

INSPECTION  OF  ARMS  IN  SERVICE,  &c. 

335.  Gauges.  The  inspecting  instruments  are  the 
standard  and  limit  gauges  of  the  bore  and  exterior  of 
the  barrel,  and  a  screw-plate  with  taps  for  the  holes  of 
the  lock-plate. 


CLASSIFICATION.  3o7 

336.  inspection.  The  following  are  the  principal 
points  to  be  attended  to  in  the  inspection  : 

Barrel.  Defects  for  which  the  barrel  must  be  con- 
demned as  unfit  for  service.  The  large  gange  entering 
the  whole  length  of  the  barrel.  The  small  or  standard 
gauge  not  entering,  unless  the  diminution  of  the  bore 
is  caused  by  the  barrel  being  indented  or  bent,  defects 
which  may  be  remedied.  A  diminution  of  the  exterior 
diameter  at  the  breech,  or  at  the  muzzle,  so  as  to  enter 
the  small  receiving  gauges  ;  this  diminution  is  0.1  inch 
at  the  breech  ;  0.03  inch  at  the  muzzle,  for  arms  with 
bayonets ;  0.045  inch  for  arms  without  bayonets.  A 
diminution  of  0.5  in  length  of  the  barrel,  splits,  cross- 
cracky  an  1  other  serious  defects,  caused  either  by  bad 
workmanship,  or  by  use. 

See  that  the  bayonet-stud  is  not  too  much  worn  or 
broken ;  that  the  cone-seat  is  perfect,  and  the  vent  un- 
obstructed. See  that  the  breech-screw  is  tight  after 
entering  five  or  six  threads ;  that  the  threads  are  sharp 
and  sound ;  that  the  body  fills  the  bore  of  the  female 
screw;  that  the  tang  is  not  broken  or  cracked  at  the 
screw-hole,  and  that  it  is  even  with  the  upper  surface 
of  the  barrel.  If  it  have  any  of  these  defects,  replace 
it  with  a  new  one. 

Cone.  See  that  the  chamfered  end  is  not  broken  or 
bruised,  and  that  the  thread  and  vent  are  in  proper 
condition. 

Bayonet.  A  bayonet  is  considered  unserviceable  if 
the  blade  is  one  inch  too  short.  See  that  it  is  sound  and 
perfect  in  all  its  parts;  that  it  fits  the  barrel;  and  that 
the  clasp  is  in  good  order,  and  turns  freely. 

Lock.     See  if  the  fixed  branches  of  the  springs  fit 

22 


338 

closely  to  the  lock-plate,  if  the  movable  branches  are 
clear  of  it,  and  if  any  of  the  parts  are  wood-bound. 
Renew  the  springs  and  the  bridle  of  the  tumbler  when 
their  pivots  are  broken.  If  the  sear  rubs  on  the  plate, 
have  it  adjusted.  The  friction  of  the  tumbler  may  be 
caused  by  the  bridle  being  badly  pierced,  in  which 
case  renew  the  bridle.  If  the  hammer  rubs  on  ono 
side,  have  it  adjusted;  if  it  rubs  everywhere,  the  ar- 
bor of  the  tumbler  does  not  project  sufficiently,  and 
the  tumbler  should  be  renewed.  If  the  notches  of  the 
tumbler  are  broken,  or  the  edges  blunt,  have  them 
dressed;  if  the  hook  of  the  tumbler  projects  beyond 
the  edge  of  the  lock-plate  when  the  hammer  is  let 
down,  the  tumbler  should  be  renewed.  The  arbor  and 
pivot  of  the  tumbler  should  fit  well  in  their  holes.  Ex- 
amine the  sear  closely,  and  have  it  renewed  when  the 
nose  is  too  thin,  or  is  worn  on  the  side  next  the  lock- 
plate,  although  it  may  be  perfect  on  the  exterior.- 

If  the  hammer  is  not  steady,  the  tumbler  should  be 
renewed.  Try  the  action  of  the  hammer,  to  see  that  it 
explodes  the  cap  with  certainty. 

Renew  the  lock-plate  when  the  screw-holes  are  too 
much,  worn  to  be  dressed  over.  Renew  every  limb 
that  is  broken  or  cracked,  the  screws  which  are  too 
much  worn,  or  of  which  the  stems  are  bent,  or  the  slits 
too  much  enlarged. 

Mountings,   See  if  the  parts  be  complete  and  sound. 

Ramrod.  See  if  it  be  sound,  and  have  a  good 
thread,  and  be  of  the  proper  length;  otherwise  re- 
place it. 

Stock.  Examine  carefully  the  bed  of  the  loch,  and  the 
holes  for  the  band  and  springs.    Press  the  thumb  against 


DURABILITY.  339 

the  facings,  to  see  if  they  are  split  at  the  holes  for  the 
side-screws,  and  renew  the  stock  if  it  be  split  at  any 
other  part  to  an  injurious  extent. 

337.  cia§siflcation.  Arms  that  have  been  in  service 
may  be  classified  as  follows  : 

1st.  Serviceable  arms, 

2d.    Arms  requiring  repairs. 

3d.    Irreparable  arms. 

Arms  in  the  hands  of  the  troops  may  be  repaired 
by  replacing  the  defective  parts  by  new  ones,  or  by 
transferring  parts  from  other  arms  of  the  same  model. 
Every  officer  in  charge  of  arms  should  be  supplied  with 
a  suitable  number  of  spare  parts  for  making  repairs  in 
the  field. 

Arms  are  considered  irreparable  when  both  the  bar- 
rel and  stock  are  unfit  for  service ;  or  when  they  require 
extensive  repairs,  and  the  parts  can  be  used  for  repairing 
other  arms. 

DURABILITY  AND  STRENGTH  OF  THE 
MUSKET-BARREL. 

338.  Durability.  Some  idea  may  be  formed  of  the 
endurance  of  small-arms  generally,  by  that  of  the  French 
musket-barrel — the  barrel  being  the  most  important 
part  of  any  arm.  It  has  been  shown  that  this  barrel 
will  bear  25,000  discharges  without  becoming  unser- 
viceable. In  time  of  war  a  musket  is  not  fired  more 
than  five  hundred  times  a  year ;  with  good  care,  there- 
fore, it  ought  to  last  fifty  years. 

The  principal  cause  of  weakness  in  a  barrel  is  the 
diminution  of  the  exterior  diameter,  at  the  breech,  by 


340  SMALL- ARMS. STRENGTH. 

wear.  This  diminution  is  limited  to  0.1  inch,  although 
a  barrel  worn  away  0.13  in.  has  borne  the  discharge  of 
two  cartridges,  placed  one  upon  the  other. 

339.  strength.  Trials  made  at  Mutzig,  in  1829,  with 
arms  sent  there  for  repairs,  show  the  following  results : 

1st.  When  a  musket-barrel  is  charged  with  a  single 
cartridge  placed  in  any  part  of  the  barrel,  or  with  two, 
or  even  three  cartridges,  inserted  regularly,  without 
any  interval  between  them,  there  is  no  danger;  with 
four  cartridges,  inserted  regularly  over  each  other,  or 
with  two  or  three  cartridges  placed  over  each  other 
with  slugged  balls,  there  is  danger  only  in  case  of  some 
defect  of  construction,  or  some  deterioration  in  the 
barrel ;  with  more  than  four  cartridges  inserted  regu- 
larly over  each  other,  or  with  two,  three,  or  four  car- 
tridges, with  intervals  between  them,  it  is  not  safe  to 
fire.  Late  experiments  with  the  rifle-musket,  show  that 
any  number  of  cartridges  can  be  placed  one  upon  the 
other,  and  the  piece  be  fired,  without  injury.  In  con- 
sequence of  the  expansive  nature  of  the  projectile, 
which  cuts  off  the  passage  of  the  flame,  but  two  charges 
will  be  inflamed,  and  their  force  will  be  expended 
through  the  vent. 

2d.  No  danger  of  bursting  is  occasioned  by  leaving 
a  ball-screw  in  the  barrel.  There  may,  be  danger  from 
a  plug  of  wood  driven  tightly  into  the  muzzle  when 
the  barrel  is  loaded  with  two  cartridges ;  or  from  a  cork 
rammed  into  the  barrel  to  a  certain  distance  from  the 
charge,  with  another  cartridge  over  it. 

Snow,  clay,  and  sand,  accidentally  introduced  into 
the  barrel,  are  not  dangerous,  if  they  lie  close  to  the 
charge ;  but  they  are  so  when  there  is  a  space  between 


STRENGTH.  341 

them  and  the  charge ;  in  this  case  sand  is  the  most  dan- 
gerous, then  clay  and  snow.  Balls  or  pieces  of  iron 
inserted  over  the  charge,  are  not  attended  with  dan- 
ger when  placed  close  to  it,  even  when  their  weight 
amounts  to  1}  lbs. ;  but  there  is  danger  from  a  piece  of 
iron  0.5  inch  square,  weighing  J-  lb.,  if  placed  20  inches 
or  more  from  the  breech. 

3d.  A  barrel,  with  a  defect  which  might  have  escaped 
the  inspector,  bore  the  explosion  of  three  cartridges, 
regularly  inserted.  In  these  trials,  barrels  originally 
0.272  inch  thick  at  the  breech  did  not  burst  when 
loaded  with  two  cartridges,  until  the  thickness  was 
reduced  to  0.169  inch,  and  with  one  cartridge,  to  0.091 
inch. 


342  PYROTECHNY. BUILDINGS,    ETC. 


CHAPTER  VII. 
PYROTECHNY. 

340.  Definition.  Pyrotechny  is  the  art  of  preparing 
ammunition  and  fireworks  for  military  and  ornamental 
purposes.  It  will  be  treated  under  the  head  of  build- 
ings, materials,  ammunition,  military  fireworks,  and 
ornamental  firework*. 

BUILDINGS,  &c. 

341.  How  arranged.  To  conduct  the  operations  of 
a  military  laboratory  with  safety  and  convenience,  the 
following  rooms  are  necessary,  viz. : — 

1st.  Furnace-room,  for  operations  requiring  the  use 
of  fire. 

2d.  Cartridge-room,  for  making  all  kinds  of  car- 
tridges. 

3d.    Filling-room,  for  filling  cartridges  with  powder. 

4th.   Composition-room,  for  mixing  compositions. 

5th.  Driving-room,  for  driving  rockets,  fuzes,  cfec. 

6th.  Packing-room,  for  putting  up  articles  for  trans- 
portation. 

7th.  Carpenters  and  tinners  shop. 

8th.  Magazine,  for  storing  powder  and  ammunition. 

A  laboratory,  like  a  powder-mill,  should  be  situated 
apart  from  inhabited  buildings ;  and,  for  convenience 
of  communication,  the  rooms,  with  the  exception  of  the 


PRECAUTIONS.  343 

farnace-room,  carpenter's  shop,  and  magazine,  should  be 
situated  under  one  roof. 

342.  Furnaces.  A  furnace  is  composed  of  a  cast-iron 
kettle,  2  feet  in  diameter,  set  in  a  fire-place  of  brick.  In 
the  field,  sods  may  replace  the  brick,  if  the  latter  cannot 
be  obtained. 

Two  kinds  of  furnaces  are  employed  in  a  laboratory ; 
in  the  first,  the  flame  circulates  around  both  bottom  and 
sides  of  the  kettle ;  in  the  second,  it  only  comes  in  con- 
tact with  the  bottom ;  the  latter  is  used  for  composi- 
tions in  which  gunpowder  forms  a  part. 

343.  Precautions.  To  prevent  accidents  in  the  oper- 
ations of  a  laboratory,  avoid,  as  much  as  possible,  the 
use  of  iron  in  the  construction  of  the  buildings,  fixtures, 
<fcc. ;  sink  the  heads  of  iron  nails,  if  used,  and  cover 
them  with  putty;  cover  the  floor  with  oil-cloth,  or  car- 
pets, and  have  it  frequently  swept.  Let  the  workmen 
in  the  powder-room  wear  socks,  and  take  them  off  when 
they  go  out.  Keep  no  more  than  the  requisite  quantity 
of  powder  in  the  laboratory,  and  have  the  ammunition 
and  finished  work  taken  to  the  magazine.  Let  powder- 
barrels  be  carried  in  hand-barrows  made  with  leather, 
or  with  slings  of  rope  or  canvas,  and  the  ammunition  in 
boxes.  Let  every  thing  that  is  to  be  moved  be  lifted, 
not  dragged  or  rolled  on  the  floor.  Never  drive  rockets, 
port-fires,  &c,  in  a  room  where  there  is  any  powder  or 
composition,  except  that  used  at  the  time.  Never  enter 
the  laboratory  at  night,  unless  it  is  indispensable,  and 
then  use  a  close  lantern,  or  wax  or  oil  light  well  trim- 
med. Allow  no  tobacco  to  be  smoked,  nor  friction 
matches  to  be  carried  in  or  around  the  laboratory. 


344  PYROTECHNY. MATERIALS. 


MATERIALS. 


344.  Classified.  Laboratory  materials  may  be  divided 
into  four  classes,  viz. : 

1st.  Those  for  producing  light,  heat,  and  explosion. 
2d.  Those  for  coloring  flames,  and  producing  brilliant 
sparks. 

3d.  Those  used  in  preparing  compositions. 

4th.  Those  used  in  making  cartridge-bags,  cases,  &,c. 

345.  1st.  class.  Nitre.  For  laboratory  use,  nitre 
must  be  reduced  to  a  fine  powder,  or  very  minute  crys- 
tals. It  is  best  pulverized  in  rolling-barrels  at  the 
powder-mills,  but  it  may  be  pulverized  by  hand,  in  the 
laboratory,  with  a  rolling-barrel,  or  by  pounding  in  a 
brass  mortar,  or  by  stirring  a  crystallizing  solution. 

Chlorate  of  potassa.  Chlorate  of  potassa  is  formed  by 
passing  a  current  of  chlorine,  in  excess,  through  lime- 
water,  and  then  treating  the  mixture  with  the  chloride 
of  potassium,  or  by  the  carbonate  or  sulphate  of  potassa. 
The  chlorate  of  potassa  and  chloride  of  calcium  are 
formed — the  former  crystallizes,  the  latter  remains  in 
solution.  It  is  soluble  in  water,  but  not  sensibly  so  in 
alcohoL  As  before  stated,  it  is  a  more  powerful  oxydiz- 
ing  agent  than  nitre ;  and,  when  mixed  with  a  combus- 
tible body,  easily  explodes  by  shock  or  friction.  It  is 
inflamed  by  simple  contact  with  sulphuric  acid,  and 
thus  affords  a  simple  means  of  exploding  mines. 

A  convenient  form  of  apparatus  for  this  purpose,  is 
a  glass  vessel  with  two  compartments,  one  containing 
sulphuric  acid,  and  the  other  chlorate  of  potassa  and 
gunpowder.     It  is  placed  near  the  surface  of  the  ground, 


FIRST    CLASS.  345 

and,  when  broken  under  the  feet  of  the  enemy,  the  two 
substances  are  brought  in  contact,  producing  fire,  which 
explodes  the  mine. 

Charcoal.  For  laboratory  use,  charcoal  may  be  made 
by  charring  wood  in  an  iron  kettle  buried  in  the  ground. 
It  may  be  pulverized  by  rolling  in  a  barrel  with  bronze 
balls,  or  by  beating  in  a  leather  bag  with .  a  maul.  It 
should  be  kept  in  close  barrels,  in  a  dry  place. 

Sulphur.  When  melted  sulphur  is  to  be  used,  care 
must  be  taken  that  it  does  not  become  thick,  which  oc- 
curs at  about  400°.  It  may  be  pulverized  in  a  rolling- 
barrel,  or  by  being  pounded  in  a  mortar  and  sifted. 
Roll  brimstone  is  better  for  melting  than  flowers  of  sul- 
phur. When  flowers  of  sulphur  are  to  be  mixed  with 
chlorate  of  potassa,  it  should  be  washed  to  remove  the 
free  sulphuric  acid.  Sulphur  retards  the  combustion  of 
compositions  to  which  it  is  added. 

Antimony.  Antimony,  or  regulus  of  antimony,  is  a 
grayish  white  metal,  easily  reduced  to  a  powder,  and, 
by  its  combustion  with  sulphur,  produces  strong  light 
and  heat ;  the  color  of  the  flame  is  a  faint  blue. 

Sulphuret  of  antimony.  Sulphuret  of  antimony  is 
mixed  with  inflammable  substances  to  render  them  more 
easily  ignited  by  flame  or  friction. 

Gunpowder.  For  compositions,  gunpowder  is  pul- 
verized, or  mealed,  by  the  rolling-barrel,  or  by  grind- 
ing with  a  muller  on  a  mealing-table,  or  by  beating  in 
a  leather  bag.  The  simple  incorporation  of  the  ingre- 
dients of  gunpowder  does  not  answer  the  desired  pur- 
pose. 

Lampblack.  Lampblack  is  the  result  of  the  incom- 
plete combustion  of  resinous   substances.      It  is  com- 


346  PYROTECHNY. MATERIALS. 

posed  of  about  80  parts  of  carbon,  and  20  of  impurities. 
It  is  employed  to  quicken  the  combustion  of  certain 
mixtures;  but,  before  it  is  used,  it  should  be  washed 
with  a  hot  alkaline  solution,  to  remove  all  traces  of  em- 
pyreurnatic  oil. 

346.  2d  cia§s.  Coloring  materials.  A  flame  is  colored 
by  introducing  into  the  composition  which  produces  it, 
a  substance,  the  particles  of  which  on  being  interspersed 
through  the  flame,  and  heated  to  the  incandescent  state, 
give  it  the  required  color.  Coloring  substances  do  not 
generally  take  part  in  the  combustion,  and  their  pres- 
ence, more  or  less,  retards  it ;  it  is  for  this  reason  that 
chlorate  of  potassa,  a  more  powerful  oxydizing  agent 
than  nitre,  is  used  in  lieu  of  it,  in  compositions  for 
colored  fires. 

Colors.  There  are  a  great  variety  of  substances 
which  give  color  to  flames,  the  principal  of  which  are, 
nitrate  and  sulphate  of  strontia  and  chloride  of  stron- 
tium, for  red ;  the  nitrate  of  baryta,  for  green ;  the  bi- 
carbonate of  soda,  for  yellow:  the  sulphate,  carbonate, 
and  acetate  of  copper,  for  blue.  Lampblack  is  employed 
to  give  a  train  of  rose-colored  fire  in  the  air,  powdered 
flint-glass  for  white  flames,  and  oxide  of  zinc  for  blue 
flames. 

Sparks.  Brilliant  sparks  are  produced  by  introducing 
into  the  composition,  filings  or  thin  chips  of  either 
wrought  iron,  cast  iron,  steel,  or  copper,  or  by  frag- 
ments of  charcoal ;  the  effect  depends  on  the  size  of  the 
particles  introduced.  The  particles  should  be  freshly 
prepared,  or  should  have  been  well  preserved  from  rust. 

347.  3d  Class.  Preparing  compositions.  Turpentine 
is  the  substance  which  exudes  from  the  freshly-cut  sur- 


PREPARING    CARTRIDGES,    ETC.  347 

face  of  a  pine  tree  in  warm  weather.  The  first  year's 
running  is  called  virgin,  or  white  turpentine  j  after  this 
it  becomes  more  hard  and  yellow. 

Spirits  of  turpentine.  This  is  the  essential  oil  ob- 
tained by  distilling  native  turpentine. 

Rosin.  This  substance  is  sometimes  called  colophony, 
and  is  the  residuum  of  the  distillation  of  turpentine. 

Tar.  Tar  is  a  semi-fluid  substance,  obtained  from  the 
heart  of  the  pine-tree  by  a  smothered  combustion,  as  in 
charcoal  pits. 

Pitch.  Pitch  is  obtained  by  boiling  tar  down  to  the 
requisite  consistency,  either  by  itself,  or  combined  with 
a  portion  of  rosin ;  it  becomes  solid  on  cooling,  but  is 
softened  by  the  heat  of  the  hand. 

Venice  turpentine.  Venice  turpentine  is  obtained 
from  the  larch ;  but  what  is  commonly  known  by  that 
name,  is  a  compound  of  melted  rosin  and  spirits  of  tur- 
pentine. The  foregoing  substances  are  chiefly  employed 
in  the  preparation  of  compositions  for  producing  light. 

Alcohol,  &c.  Alcohol  (spirits  of  wine),  brandy, 
whiskey,  or  vinegar,  is  used  for  mixing  compositions  in 
which  nitre  enters,  because  this  salt  is  but  slightly  sol- 
uble in  these  liquids. 

Gum-arabic.  Gum-arabic  in  solution  is  employed  to 
give  body  to  certain  compositions.  It  retards  combus- 
tion ;  and,  as  the  solution  is  liable  to  spontaneous  de- 
composition, it  should  only  be  prepared  as  wanted. 

Beeswax  and  mutton  tallow  are  employed  chiefly  in 
mixing  compositions  intended  to  produce  heat  and  light. 

348.   4th  Class.    Preparing  cartridges  &c.  The  size  and 

strength  of  laboratory  paper  is  regulated  by  the  use  to 
which  it  is  applied.     It  is  arranged  in  live  classes,  the 


348       PYEOTECHNY. AMMUNITION    FOE    SMALL- AEMS. 

strongest  being  for  cannon-cartridges,  and  the  thinnest 
for  musket-cartridges. 

Paste.  Ordinary  paste  is  made  of  rye  flour,  stirred 
and  boiled  in  water. 

Flannel,  wildbore,  or  serge,  for  cartridge-bags,  should 
be  made  entirely  of  wool  or  silk ;  the  fabric  should  be 
soft,  and  closely  woven,  to  prevent  the  powder  from 
sifting  out. 

Fabrics  of  cotton  and  flax  are  not  used,  because  the 
powder  sifts  through  them,  and  they  are  more  apt  to 
leave  fire  in  the  gun  than  woollen  stuffs. 

Canvas.  Canvas  is  used  for  sacks,  &c. ;  it  should  be 
strong  and  closely  woven. 

Twine,  &c.  Twine  should  be  strong,  smooth,  and 
well  twisted. 

AMMUNITION  FOR  SMALL-ARMS. 

349.  Bullets.  Bullets,  for  the  military  service,  are 
made  by  pressure.  To  prepare  the  lead  for  the  press,  it 
is  cast  into  cylinders,  or  drawn  out  into  a  wire  of  a 
diameter  somewhat  less  than  that  of  the  bullet.  A 
piece,  just  sufficient  to  make  a  bullet,  is  then  cut  off, 
and  transferred  by  a  movable  arm  to 
a  pair  of  dies  (a  a,  fig.  Ill),  which 
are  firmly  closed  by  two'  movable 
wedges  (b  i) ;  as  soon  as  this  is  done, 
the  punch  (e)  descends  upon  the 
lead  and  forms  the  cavity  at  the  base  Fig.  in. 

of  the  bullet.  To  disengage  the  bullet,  the  punch  rises, 
but  before  it  has  completely  cleared  the  cavity,  the  dies 
open,  and  the  bullet  falls  into  its  receptacle. 


PACKING. 


349 


One  press  is  capable  of  making  3,000  bullets  in  an 
k  hour.     Bullets  may  be  also  cast  in  moulds,  and  after- 
ward swaged  in  a  die  to  the  proper  size  and  shape. 

350.  Cartridge.  After  the  bullet  has  been  greased 
(see  page  315),  it  is  made  up  into  a  cartridge  along 
with  its  charge  of  powder.  The  rifle-musket  cartridge 
(fig.  112)  is  formed  of  three  parts;  the  bullet  (£),  the 
cylinder  («),  wThich  contains  the  powder,  and  the  wrap- 
per, which  unites  the  cylinder  with  the  bul- 
let. The  bottom  of  the  cylinder  should  be 
perfectly  tight,  to  prevent  the  powder  from 
sifting  through. 

To  use  this  cartridge,  tear  off  the  fold  of 
the  wrapper  and  pour  the  powder  into  the 
bore,  break  the  cartridge  at  the  junction  of 
the  bullet    and  powder-cylinder,  force  out      Fig  112. 
the  bullet  by  pressing  with  the  thumb  and  forefinger, 
and  insert  it  in  the  bore.     Care  should  be  taken  to  pour 
all  of  the  powder  into  the  barrel. 

351.  Buckshot  cartridge.  The  number  of  projec- 
tiles in  a  buckshot  cartridge  is  twelve,  or  four  layers  of 
three  each  (fig.  113).  The  layers  are  kept  in 
position  by  passing  one  half  hitch  of  the  chok- 
ing thread,  between  every  two  layers;  the 
thread  is  secured  by  passing  two  half-hitches 
around  the  upper  layer.  For  rifled  arms,  the 
shot  end  of  the  cartridge  should  be  dipped  in 
the  composition  used  for  lubricating  bullets  ; 
with  this  precaution  all  leading  of  the  grooves  Fig. 
will  be  avoided.  Buckshot  cartridges  are  principally 
used  in  Indian  warfare,  and  especially  in  night-firing. 

352.  Packing.     Small-arm  cartridges  are  wrapped  in 


350       PYROTECHNY. AMMUNITION    FOR    SMALL- ARMS. 


bundles  of  ten  each,  and  packed  in  boxes  of  1,000.  The 
date  and  place  of  fabrication  are  marked  on  the  inside 
of  the  cover,  and  the  contents,  on  the  outside  of  one  end 
of  the  packing-box. 

353.  Pistol  cartridge.  The  powder-cylinder  of  Colt's 
cartridge  is  made  of  combustible  paper  (prepared  after 
the  manner  of  gun-cotton)  ;  it  is  attached  to  the  base  of 
the  bullet,  and  is  inserted  in  the  piece  entire. 

354.  Percussion-caps.  The  military  percussion-cap 
is  made  slightly  conical,  to  fit  the  cone  tightly,  and  has 
a  rim  around  the  open  end  for  convenience  in  handling. 
It  is  made  of  sheet  copper,  which  is  first  cut  into  the 
form  of  an  equilateral  cross  (a,  fig.  114), 
and  then  transferred  to  a  die,  where  it  is 
punched  into  the  required  shape  (b).  It  is 
charged  with  half  a  grain  of  powder,  com- 
posed of  equal  parts  of  nitre  and  fulminate 
of  mercury  /  the  object  of  the  nitre  being 
to  retard  the  combustion  of  the  composition, 
and  give  density  to  the  flame. 

The  composition  is  pressed  into  the  cap  in  a  dry 
state,  and  covered  with  a  drop  of  shellac  varnish  to  fix 
it  in  its  place  and  protect  it  from  moisture.  With  the 
exception  of  varnishing,  all  the  operations  of  making 
percussion-caps  are  performed  by  a  single  machine,  at 
the  rate  of  50,000  per  day.  Percussion  caps  were  in- 
vented in  the  United  States,  in  1817. 

355.  uiaynard's  Primer.  This  primer  is  made  by 
indenting  a  sheet  of  paper  at  regular  intervals  (a  a,  fig. 

115),  filling  each  indenta- 
tion with  a  small  charge 
of  percussion  powder,  and 


Fig.  114. 


STAND    OF    AMMUNITION. 


351 


covering  the  whole  with  another  sheet  of  paper,  firmly 
pasted  on.  The  sheet  is  then  cut  into  strips,  each  strip 
containing  60  primers  in  a  single  row,  and,  to  protect 
it  from  the  moisture,  it  is  covered  with  a  thick  coat  of 
shellac  varnish. 


FIELD   AND   MOUNTAIN  AMMUNITION. 

356.  Composition.  Ammunition  for  the  field-service 
is  composed  of  solid  shot,  shells,  spherical-case  shot,  and 
canister-shot;  in  the  mountain  service,  the  solid  shot 
are  omitted. 

For  convenience  in  loading,  and  safety  in  transporta- 
tion, cannon  ammunition  should  be  prepared  in  a  pe- 
culiar manner,  and  with  great  care. 

357.  stand  of  ammunition.  A  stand  of  ammunition 
is  composed  of  the  projectile  (a,  fig.  116), 
the  sabot  (Z>),  the  straps  (<?),  the  cartridge- 
bag  (d),  and  the  cylinder  (e)  and  cap. 
The  preparation  of  the  projectile  itself, 
is  described  in  chapter  II. 

Sabot.  The  sabot  is  a  thick,  circular 
disk  of  wood,  to  which  the  cartridge-bag 
and  projectile  are  attached. 

For  a  spherical  projectile,   the   sabot 
has  a  spherical  cavity  (a,  fig.  117),  and  a  circular  groove 

to  which  the  cartridge-bag  is 
tied;  in  the  canister-sabot, 
the  spherical  cavity  is  omit- 
ted, and  a  circular  offset  (b) 
is  added. 
The  effects  of  a   sabot  are: — 1st.    To   prevent  the 


Fig.  116. 


Fig.  117. 


352    PYROTECHNY. FIELD  AND  MOUNTAIN  AMMUNITION. 

formation  of  a  lodgment  in  the  bore.  2d.  To  moderate 
the  action  of  the  powder  on  the  projectile;  and,  3d,  To 
prevent  the  projectile  from  moving  from  its  place.  In 
consequence  of  the  scattering  of  the  fragments,  it  is 
dangerous  to  use  the  sabot  in  firing  over  the  heads  of 
one's  own  men. 

Straps.  The  projectile  is  secured  by  two  tin  straps, 
fastened  at  the  ends  with  tacks  driven  into  the  sabot. 
The  straps  cross  each  other  at  right  angles ;  for  solid 
shot,  one  strap  passes  through  a  slit  in  the  other;  for 
hollow  projectiles,  both  straps  are  fastened  to  a  tin  ring 
which  surrounds,  the  fuze-hole. 

Cartridge-bag.  The  materials  of  which  cartridge-bags 
are  made  are  described  on  page  348.  A  cartridge-bag 
for  the  field  service  is  made  of  two  pieces — a  rectangu- 
lar piece  for  the  sides,  and  a  circular  piece  for  the  bot- 
tom. The  rectangular  piece  should  be  cut  in  the  direc- 
tion of  the  warp,  to  prevent  the  bag  from  stretching  in 
the  direction  of  its  diameter;  the  seams  should  be 
sewed  with  woollen  yarn,  12  stitches  to  the  inch,  and 
the  edges  should  be  basted  down,  to  prevent  the  pow- 
der from  sifting  through.  The  charge  is  determined  by 
measurement. 

Cylinder  and  cap.  The  cylinder  and  cap  are'  made  of 
stout  paper.  The  cylinder  is  used  to  give  stiffness  to 
the  cartridge  at  the  junction  of  the  sabot  and  bag  ;  the 
cap  covers  the  exposed  portion  of  the  bag,  and  is  drawn 
off  before  loading,  and  placed  over  .the  projectile,  or 
thrown  away.  The  cap  is  made  by  cutting  off  a  por- 
tion of  the  cylinder,  and  choking  one  end.  The  car- 
tridge-bag is  attached  to  the  projectile  by  tying  it 
around  the  grooves  of  the  sabot  with  twine. 


CARTRIDGE-BAGS.  353 

358.  strapped  a  mm  unit  ion.  Ammunition  thus  pre- 
pared is  called  fixed  ammunition.  In  the  large  field 
howitzers,  it  is  not  convenient  to  unite  the  cartridge- 
bag  and  projectile,  on  account  of  the  difficulty  of  pack- 
ing them  in  the  ammunition  chests ;  the  bag  and  pro- 
jectile are  therefore  carried  separately.  The  projectile 
is  attached  to  a  sabot  without  grooves ;  and,  to  give  a 
proper  form  to  the  cartridge-bag  the  mouth  is  closed 
with  a  cartridge-Mock,  which  resembles  a  sabot;  hence 
the  name  strapped  ammunition. 

359.  Packing,  &c.  As  soon  as  ammunition  is  finished 
it  should  be  gauged,  to  see  that  it  is  of  the  proper  cali- 
bre; it  is  afterward  packed  in  boxes  containing  ten 
rounds  each,  with  scraps  of  paper,  or  tow,  well  rammed 
into  the  interstices. 

Ammunition  may  be  distinguished  by  the  color  of 
the  cap;  for  spherical-case  shot,  it  is  red;  for  shells, 
black ;  and  for  solid-shot  and  canister,  it  is  the  natural 
color  ot  the  paper.  The  outside  of  the  packing-box  is 
colored  red  for  spherical-case  shot ;  black  for  shells ; 
olive  for  shot ;  and,  for  canister,  the  natural  color  of  the 
wood ;  besides  this,  it  is  marked  with  the  number  and 
character  of  the  contents  in  letters  and  figures. 


SIEGE  AND  SEA-COAST  AMMUNITION. 

360.  Cartridge-bags.  On  account  of  the  great  weight 
of  siege  and  sea-coast  ammunition,  the  cartridge-bag  and 
projectile  are  carried  separately. 

The  cartridge-bags  for  large  charges  of  powder  are 
made  of  two  pieces  of  woollen  stuff  (iig.  118),  or  of  a 

23 


354    PYROTECHNY. FIELD  AND  MOUNTAIN  AMMUNITION. 


Fig,  118. 


paper  tube,  with  woollen  cloth  bottom. 
The  former  are  preferred  for  rapid  firing. 
For  sea-coast  howitzers,  the  bag  should 
fill  the  chamber ;  if  the  piece  be  fired 
with  a  reduced  charge,  a  cartridge-block 
should  be  inserted  into  the  bag  to  give 
it  proper  size.  For  mortars  the  bag  is 
only  used  to  carry  the  powder,  and  when  the  piece  is 
loaded,  the  powder  is  poured  into  the  chamber ;  bags  of 
any  suitable  size  will  answer  for  this  service.  For  hot- 
shot cartridges,  bags  are  made  double,  by  putting  one 
bag  within  another.  Care  should  be  taken  to  see 
that  the  bags  are  free  from  holes. 

For  ricochet  firing,  or  other  occasions  when  very  small 
charges  are  required,  a  cartridge-bag  of  inferior  calibre 
may  be  used  ;  or  else,  after  the  charge  is  poured  into  the 
bag,  place  it  on  another  bag  filled  with  hay,  pressing 
it  with  the  hands  to  reduce  the  diameter ;  after  having 
shaken  this  bag  down,  and  rolled  and  flattened  the  empty 
parts  of  the  two  bags,  tie  them  with  woollen  yarn,  like 
a  bundle  of  musket-cartridges,  placing  the  knot  on  top. 
361.  strapping  §heii§,  &c.  In  the  siege  and  sea-coast 
services,  solid  shot  are  transported  and  loaded  loosely, 
but  hollow  projectiles  are  strapped 
to  sabots  to  prevent  the  fuze  from 
coming  in  contact  with  the  powder 
of  the  charge.  The  sabots  are  made 
from  thick  plauk  (jig.  119),  and  the 
straps  are  fastened  as  in  the  field- 
service.  The  fuze-hole  is  placed  in 
one  of  the  angles  of  the  straps,  in 
Fig-  119,  such    a  manner  that   its  axis  shall 


wads.  355 

make  an  angle  of  45°  with  that  of  the  sabot.  In  load- 
ing, care  should  be  taken  to  place  the  fuze-hole  up- 
permost. 

When  there  are  no  ears  on  the  projectile,  a  handle  of 
rope-yarn  is  attached  to  two  loops  soldered  to  one  of 
the  straps,  or  it  is  passed  through  two  holes  bored  in 
the  bottom  of  the  sabot. 

362.  Filling  shells.  Shells  are  filled  with  cannon- 
powder  alone,  or  with  cannon-powder  and  some  kind 
of  incendiary  composition.  Before  filling,  the  shell 
should  be  inspected,  to  see  that  it  is  dry,  clean,  and  free 
from  defects.* 

The  service  bursting-charges  of  powder  for  the  larger 
shells  are : — 

15 -INCH.  13-INCH.        10-INCH.  8-INCH. 

Mortar-shell, 7  lbs.     5  lbs.     2-J-  lbs. 

Columbiad-shell,  .    11  lbs.        "        3  lbs.     1-L  lbs. 

363.  Wads.  Junk  wads  having  been  found  detri- 
mental in  ordinary  firing,  are  only  used  for  proving 
cannon. 

For  firing  hot-shot,  a  hay  wad,  soaked  in  water,  is 
interposed  between  the  powder  and  shot.  The  wad  is 
made  by  twisting  the  hay  into  a  rope,  winding  the  rope 
into  a  coil,  which  is  driven  into  wooden  moulds  of  the 
proper  size.  To  preserve  the  size  and  form  of  the  wad 
it  is  afterward  wrapped  tightly  with  rope-yarn. 

Grommets.  Grommets,  or  ring  wads,  are  useful  in 
increasing  the  accuracy  of  fire,  and  keeping  the  projec- 
tile in  its  place  when  the  piece  is  moved  or  depressed. 

*  To  find  the  quantity  of  powder  which  a  shell  will  contain,  multiply  the  cube  of 
the  interior  diameter  of  the  shell  in  inches  by  0.01744,  the  result  is  the  weight 
of  powder  in  pounds. 


356  PYKOTECHNY. MILITARY   EIREWOKKS. 

It  is  made  by  bending  a  strand  of  rope  into  the  form 
of  a  circle,  and  wrapping  it  with  rope-yarn.  The  size 
of  the  ring  is  the  full  diameter  of  the  bore,  that  it  may 
fit  tightly.  This  wad  is  attached  to  the  front  of  the 
projectile  with  twine;  or,  it  may  be  inserted  after  the 
projectile,  like  ordinary  wads. 

MILITAEY  FIEEWOEKS. 

364.  Comprise  what.  Military  fireworks  comprise 
preparations  for  the  service  of  cannon  ammunition,  and 
for  signal,  light,  incendiary,  and  defensive  and  offensive 
purposes. 

365.  Compositions.  The  term  composition  is  applied 
to  all  mechanical  mixtures  which,  by  combustion,  pro- 
duce the  effects  sought  to  be  attained  in  pyrotechny.  If 
these  compositions  be  examined,  it  will  be  found  that 
many  of  them  are  derived  from  gunpowder,  by  an  ad- 
mixture of  sulphur  and  nitre,  in  proportions  to  suit  the 
required  end;  a  German  writer  has  even  proposed  to 
extend  this  method  to  the  formation  of  all  the  principal 
compositions,  but  the  simplicity  of  the  plan  has  never 
been  fully  realized  in  practice. 

Preparation.  Compositions  are  prepared  in  a  dry  or 
liquid  form ;  in  either  case  it  is  necessary  that  the  in- 
gredients should  be  pure,  and  thoroughly  mixed. 

For  dry  compositions,  the  ingredients  are  pulverized 
separately,  on  a  m^^m^-table,  with  a  wooden  muller; 
they  are  then  weighed,  and  mixed  with  the  hands,  and 
afterward  passed  three  times  through  a  wire  sieve  of  a 
certain  fineness.  When  a  highly  oxydizing  substance, 
as  the  chlorate  of  potassa,  is  present,  great  care  must  be 


COMPOSITIONS.  357 

observed  in  mixing,  to  avoid  friction  or  blows,  which 
might  lead  to  an  explosion.  When  coarse  charcoal,  or 
metals  in  grains  are  used,  they  should  be  added  after 
the  other  ingredients  have  been  mixed  and  sifted. 

For  the  liquid  form.  When  it  becomes  necessary  to 
use  fire  to  melt  the  ingredients,  the  greatest  precaution 
is  necessary  to  prevent  accidents,  particularly  when 
gunpowder  enters.  The  dry  parts  of  the  composition 
may  be,  generally,  mixed  together  first,  and  put  by 
degrees  into  the  kettle,  when  the  other  ingredients 
are  fluid,  stirring  well  all  the  time.  When  the  dry 
ingredients  are  very  inflammable,  the  kettle  must 
not  only  be  taken  from  the  fire,  but  the  bottom  must 
be  dipped  in  water,  to  prevent  the  possibility  of  acci- 
dents. 

How  disposed.  To  give  a  portable  form  to  composi- 
tions, they  are  enclosed  in  cases,  cast  in  moulds,  or  at- 
tached to  cotton  yarn,  rope,  &c. 

•  Cases.  Cases  are  generally  paper  tubes,  made  by 
covering  one  side  of  a  sheet 
of  paper  with  paste,  or  gum- 
arabic,  wrapping  it  around  a 
former,  and  rolling  it  under  a 
flat  surface  until  all  the  layers 
adhere  to  each  other  (fvg.  120).  The  quality  of  the 
paper,  and  the  thickness  of  the  sides  of  the  case,  should 
depend  upon  the  pressure  of  the  gases  evolved  in  the 
burning. 

Filling.  To  fill  a  case,  it  is  first  cut  to  the  proper 
length,  and  placed  in  a  mould ;  the  composition  is  then 
poured  in,  a  ladleful  at  a  time,  and  each  ladleful  is 
packed  by  striking  a  certain  number  of  blows  on  a  drift 


Fig.   120. 


358  -PYROTECITNT. MILITARY    FIREWORKS. 

with  a  mallet  of  a  given  weight.  The  height  of  each 
ladleful  of  composition  should  be  about  equal  to  a  sin- 
gle diameter  of  the  bore  of  the  case. 

Drifts,  &c.       Small   drifts,  receiving   heavy  blows, 
should  be  made  of  steel,  and 
tipped  with  bronze  (fig.  121)  ; 


large  drifts  may   be   made   of  Fig.  121. 

wood  or  bronze,  depending  on  the  force  of  the  blow. 
In  driving  highly  inflammable  compositions,  as  that  of 
the  rocket,  care  should  be  taken  to  settle  the  drift,  so 
as  to  exclude  the  air  before  striking  with  the  mallet,  as 
the  heat  generated  by  the  sudden  condensation  of  air 
might  be  sufficient  to  ignite  the  composition. 

Preliminary  tests  of  all  new  materials  should  be  made 
by  burning  one  or  more  specimens  of  the  composition, 
and  the  proportions  of  the  ingredients  corrected,  if 
necessary. 

Vent,  &c.  The  length  of  the  flame  from  a  given  com- 
position depends  on  the  size  of  the  vent  and  the  extent 
of  the  burning  surface.  The  vent  is  made  small  by 
choking  the  end  of  the  case  with  stout  twine ;  and  the 
burning  surface  is  increased  by  driving  the  composition 
around  a  spindle,  which,  on  being  withdrawn,  leaves  a 
conical-shaped  cavity.  A  vent  may  be  also  formed  by 
driving  in  moist  plaster  of  Paris  or  clay,  and  boring  a 
hole  in  it  with  a  gimlet.  If  the  end  of  the  case  is  to  be 
closed  up  entirely  the  boring  is  omitted. 

366.  For  ammunition.  The  preparations  for  the  ser- 
vice of  ammunition  are  slow-match,  quick-match,  port-fires, 
friction-tubes,  and  fuzes. 

367.  Slow-match.  Slow-match  is  used  to  preserve 
fire.     It  may  be  made  of  hemp  or  cotton  rope ;  if  made 


FRICTION-TUBE.  359 

of  hemp,  the  rope  is  saturated  with  acetate  of  lead,  or 
the  lye  of  wood-ashes;  if  made  of  cotton,  it  is  only 
necessary  that  the  strands  be  well  twisted.  Slow-match 
"burns  from  four  to  five  inches  in  an  hour. 

368.  Quick-match.  Quick-match  is  made  of  cotton 
yarn  (candle-wick)  saturated  with  a  composition  of 
mealed  powder  and  gummed  spirits ;  after  saturation, 
the  yarn  is  wound  on  a  reel,  sprinkled  (dredged)  with 
mealed  powder,  and  left  to  dry. 

It  is  used  to  communicate  fire,  and  "burns  at  the  rate 
of  one  yard  in  thirteen  seconds.  The  rate  of  burning 
may  be  much  increased  by  enclosing  it  in  a  thin  paper 
tube  called  a  leader.   ' 

369.  Port-fires.  A  port-fire  is  a  paper  case  containing 
a  composition,  the  flame  of  which  is  capable  of  quickly 
igniting  primers,  quick-match,  &c. 

The  composition  consists  of — 


NITRE. 

SULPHUR. 

MEALED   POWDER. 

6 

3 

1 

A  port-fire  is  about  22  inches  long,  and  burns  with 
an  intense  flame  for  ten  minutes. 

370.  Friction-tube.  The  friction-tube  is  at  present 
the  principal  preparation  for  firing  cannon ;  its  advan- 
tages are  portability  and  certainty  of  fire.  It  also  affords 
the  means  of  firing  a  piece  situated  at  a  distance,  and 
does  not  attract  the  notice  of  the  enemy's  marksmen  at 
night. 

It  is  composed  of  two  brass  tubes  soldered  at  right 


360 


PYROTECH1SV. MILITARY    FIREWORKS. 


angles  (rig.  122).  The  upper,  or  short  tube 
contains  a  charge  of  friction  powder,  and 
the  roughed  extremity  of  a  wire  loop  (a) 
(the  extremity  is  shown  by  fig.  Z>) ;  the  long 
tube  is  filled  with  rifle  powder,  and  is  in- 
serted in  the  vent  of  the  piece.  When  the 
extremity  of  the  loop  is  violently  pulled  by 
means  of  a  lanyard,  through  its  hole  in  the 
long  tube,  sufficient  heat  is  generated  to  ig- 
nite the  friction  powder  which  surrounds  it,  and  this 
communicates  with  the  grain-powder  in  the  long  tube. 
The  charge  of  grained  powder  has  sufficient  force  to 
pass  through  the  longest  vent,  and  penetrate  several 
thicknesses  of  cartridge-cloth.  The  composition  of  fric- 
tion powder  is:  — 


Fig.  122. 


CHLORATE    OF   POTASS  A. 

SULPHURET  OF  ANTIMONY. 

2 

1 

formed  into  a  paste  with  gum- water. 

371.  Fuzes.  Fuzes  are  the  means  used  to  ignite  the 
bursting-charge  of  a  hollow  projectile  at  any  desired 
moment  of  its  flight ;  they  may  be  classified  according 
to  their  mode  of  operation,  as  percussion,  concussion, 
and  time-fuzes. 

Time-fuze.  This  fuze  is  composed  of  a  case  of  paper, 
wood,  or  metal,  enclosing  a  column  of  burning  compo- 
sition, which  is  set  on  fire  by  the  discharge  of  the  piece, 
and  which,  after  burning  a  certain  time,  communicates 
with  the  bursting-charge. 

Its  successful  operation  depends  on  the  certainty  of 


FUZES.  361 

ignition,  the  uniformity  of  burning,  and  the  facility 
with  which  its  flame  communicates  with  the  bursting- 
charge. 

Composition.  The  ingredients  of  all  time-fuze  compo- 
sitions are  the  same  as  for  gunpowder,  but  the  propor- 
tions are  varied  to  suit  the  required  rate  of  burning- 
Pure  mealed  powder  gives  the  quickest  composition, 
and  the  others  are  derived  from  it  by  the  addition  of 
nitre  and  sulphur  in  certain  quantities. 

The  rate  of  burning  of  a  column  of  fuze  composition 
depends  on  the  purity  and  thorough  incorporation  of  the 
materials,  and  on  its  density.  These  qualities  are  best 
secured  by  procuring  the  materials  from  the  powder, 
mills  ready  mixed,  and  driving  them  with  a  press  of 
peculiar  construction. 

Three  kinds  of  time-fuzes  are  employed  in  the  United 
States  service,  viz.:  the  mortar-fuze,  the  Bormann-ftize, 
and  the  sea-coast  fuze. 

Mortar-fuze.  The  case  of  the  mortar-fuze  is  made  of 
beech-wood,  turned  in  a  lathe  to  a  conical  shape,  and 
bored  out  nearly  to  the  bottom  to  receive  the  composi- 
tion (fig.  123).  The  composition  is  driven  with 
fifteen  blows  of  the  mallet.  The  bore  is  en- 
larged at  the  top  to  receive  a  priming  of  mealed 
powder  moistened  with  alcohol.  To  protect  the 
priming  from  injury  by  moisture,  the  top  of  the 
fuze  is  covered  with  a  cap  of  water-proof  paper, 
on  which  is  marked  the  rate  of  burning  of  the 
composition.  The  exterior  is  divided  into  inches  Fig.  123. 
and  tenths,  to  guide  the  gunner  in  regulating  the  time 
of  burning.  This  operation  is  generally  performed  be- 
fore the  fuze  is  driven  into  the  fuze-hole  of  the  shell,  by 


362 


PYROTECHNY. MILITARY    FIREWORKS. 


cutting  it  off  with  a  saw,  or  boring  into  the  composition 
with  a  gimlet. 

If  the  fuze  be  driven,  the  column  of  composition  may 
be  shortened  by  taking  a  portion  from  the  top  with  the 
fuze-auger. 

372.  Bormann-fnze.  This  fuze  is  the  invention  of 
an  officer  of  the  Belgian  service.  The  case  is  made  of 
an  alloy  of  tin  and  lead,  cast  in  iron  moulds.  Its  shape 
is  that  of  a  thick,  circular  disk  ;  and  a  screw  thread  is 
cut  upon  its  edge,  by  which  it  is  fast- 
ened into  the  fuze-hole  of  the  project- 
ile. (See  figure  124.)  The  upper  sur- 
face is  marked  with  two  recesses  (a  a), 
and  a  graduated  arc.  The  former  are 
made  to  receive  the  prongs  of  a  screw- 
driver ;  and  the  latter  overlies  a  circu- 
lar groove,  filled  with  mealed  powder, 
tightly  pressed  in  and  covered  with 
metal  cap.  The  only  outlet  to  the  groove  containing 
the  mealed  powder  is  under  the  zero  of  the  graduation ; 
this  outlet,  or  channel  (<?),  is  filled  with  rifle  powder, 
and  leads  down  to  a  circular  recess  (7>),  which  is  filled 
with  musket  powder,  and  covered  with  a  perforated 
disk  of  tin.  To  enable  this  fuze  to  resist  the  shock  of 
discharge,  and  at  the  same  time  to  increase  the  effect  of 
a  small  bursting-charge,  the  lower  portion  of  the  fuze- 
hole  is  closed  with  a  perforated  disk  (e). 

Before  the  projectile  is  inserted  into  the  piece,  a  cut 
is  made  across  the  graduated  portion,  laying  bare  a 
small  proportion  of  the  mealed  powder,  which,1  being  ig- 
nited by  the  flame  of  the  charge,  burns  in  both  direc- 
tions until  the  outlet  is  reached  and  the  grain  powder 


Fig.   124. 


SEA-COAST   FUZE.  363 

ignited.  The  graduations  are  seconds  and  quarter  sec- 
onds, and  the  time  of  burning  of  the  fuze  depends  on 
the  length  of  the  column  of  mealed  powder  included 
between  the  incision  and  outlet.  If  the  metal  covering 
be  not  cut,  the  projectile  may  be  fired  as  a  solid  shot 
The  Bormann-fuze  is  used  for  the  field  and  siege  ser- 
vices, and  is  found  to  be  accurate  and  reliable,  especially 
for  spherical-case  shot.* 

373.  Sea-coa§t  fuzc.-f-  The  sea-coast  fuze  is  princi- 
pally distinguished  from  the  mortar-fuze 
by  having  a  metal  cap,  constructed  to  pre- 
vent the  burning  composition  from  being 
extinguished  when  the  projectile  strikes 
against  water. 

It  is  composed  of  a  brass  plug  (ay  fig. 
125),  which  is  firmly  driven  into  the  fuze- 
hole  of  the  projectile  ;  a  paper-fuze  (7>),  in- 
serted into  the  plug,  with  the  fingers,  im-        Bg.  125. 
mediately  before  loading  the  piece ;  and  a  water-cap  (<?), 
screwed  into  the  plug  after  the  paper-fuze  has  been 
inserted. 

The  water-cap  is  perforated  with  a  crooked  channel, 
which  is  filled  with  mealed  powder ;  the  mealed  powder 
communicates  fire  to  the  paper-fuze,  and  the  angles  of 
the  channel  break  the  force  of  the  water. 

The  top  of  the  cap  has  a  recess  which  is  filled  with  a 
priming  of  mealed  powder,  and  is  covered  with  a  disk 


*  The  time  of  burning  of  the  Bormann-fuze,  not  being  long  enough  for  the  gen- 
eral service  of  rifle  projectiles,  the  paper  time-fuze  (b.  fig.  125)  is  used  instead  of  it 
for  all  of  those  projectiles  which  require  the  time-fuze.  It  is  inserted  into  a  zinc 
plug,  which  is  screwed  into  the  fuze-hole  of  the  projectile. 

f  This  valuable  fuze  was  invented  by  the  late  Mr.  Cyrus  Alger,  of  Boston,  Mas- 
sachusetts, in  1842. 


364 


PYROTECHNT. MILITARY   FIREWORKS. 


of  sheet  lead  to  prevent  accidental  ignition ;  before  load- 
ing, this  disk  is  removed.  The  time  of  burning  is  reg- 
ulated by  the  proportion  of  the  ingredients  of  the 
composition ;  and  this  is  indicated  by  the  number  of 
seconds  marked  on  the  paper  case.  In  firing  over  land, 
the  water-cap  is  omitted,  and  the  brass  plug  may,  for 
the  sake  of  economy,  be  replaced  by  a  wooden  one. 
One  advantage  of  this  form  of  fuze  is,  that  the  bursting- 
charge  may  be  put  in,  or  taken  out,  after  the  fuze-plug 
has  been  driven. 

374.  Concii§§ion-fuze.  A  concussion-fuze  is  made 
to  operate  by  the  shock  of  the  discharge,  or  by  the 
shock  experienced  in  striking  the  object,  and  is  applica- 
ble to  spherical  projectiles.  One  of  the  simplest,  as  well 
as  one  of  the  most  effective,  concussion-fuzes  is  that  in- 
vented by  Captain  Splingard,  of  the  Belgian  service; 
and  for  the  purpose  of  illustrating  the  principle  of  this 
class  of  fuzes,  it  may  be  proper  to  give  an  outline  of  its 
construction. 

It  is  composed  of  two  principal  parts,  the  wooden 
plug,  and  the  paper-fuze.     The  chief  pecu- 
liarity lies  in  the  arrangement  of  the  paper- 
fuze.     The   case    (#,  Hg.    126),  is  made  of 
paper,  rendered  incombustible  by  a  solution 
of  sulphate  of  ammonia  and  alum,  and  filled 
with  fuze  composition  (7>)  of  variable  quick- 
ness of  burning.     A  long  cavity  is  formed  in 
the  lower  part  of  the  composition,  by  driving 
it  around  a  spindle,  as  in  a  rocket ;  this  cav- 
ity is  filled  with  moist  plaster  of  Paris,  and  a      rig.  12 6. 
long  needle  is  inserted  in  it,  nearly  to  the  bottom  of  the 
plaster,  forming  a  tube  (<?)  enclosed  in  and  supported 


PERCUSSION-FUZE.  365 

by  the  composition.  The  composition  is  ignited  in  the 
usual  way,  at  the  top,  and,  as  it  burns  away,  leaves  a 
portion  of  the  plaster  tube  unsupported ;  when  the  shell 
strikes  its  object,  the  shock  breaks  off  the  unsupported 
part  of  the  tube,  and  the  flame  of  the  composition  im- 
mediately communicates  with  the  bursting-charge ;  if 
the  tube  do  not  break,  the  composition  burns  up,  and  the 
bursting-charge  is  ignited,  as  in  an  ordinary  time-faze. 
The  upper  portion  of  the  composition  burns  away  quick- 
ly, in  order  to  leave  the  tube  unsupported  soon  after 
the  projectile  leaves  it  piece. 

375.  Percu§sioii-fuse.  A  percussion-fuse  explodes  by 
the  striking  of  some  particular  point  of  a  projectile 
against  an  object,  as  in  the  case  of  rifle-cannon  projectiles. 
One  of  the  best  and  simplest  forms  of  this  kind  of 
fuze  is  the  ordinary  percussion-cap  placed  on  a  cone 
affixed  to  the  point  of  the  projectile.  The  piece  to 
which  the  cone  is  attached  may  be  fixed  or  movable ; 
in  either  case,  the  apparatus  should  be  covered  with  a 
safety-cap  to  prevent  the  percussion-cap  from  taking 
fire  by  the  discharge  of  the  piece. 

Fig.  127  represents  a  fuze  of  the  per- 
cussion kind,  in  which  b  is  a  movable 
cone-piece,  bearing  a  musket-cap  (<?)  ;  and 
a  is  the  safety-cap  which  covers  the  fuze- 
hole.  When  the  projectile  is  set  in  mo- 
tion, the  cone-piece,  or  "  plunger,"  by  its 
inertia,  presses  against  the  shoulders  of 
Fig.  m.         ^e   fuze_h0le.-*   when   its   motion  is  ar- 

*  The  plunger  is  kept  in  its  place  by  a  paper  washer,  the  diameter  of  which 
is  a  little  larger  than  that  of  the  fuze-hole ;  before  loading  the  piece,  the  plunger 
should  be  examined,  to  see  that  it  is  not  clogged  by  the  powder  contained  in  the 
shell. 


366  PYR0TECHTSY. FIREWORKS    FOR   SIGNALS. 

rested,  the  inertia  of  the  cone-piece  causes  the  percus- 
sion-cap to  impinge  against  the  safety-cap,  which  pro- 
duces explosion.  The  explosion  of  the  projectile  may 
be  made  to  take  place  at  any  desired  time,  after  the  ex- 
plosion of  the  cap,  by  interposing  grain,  or  mealed  pow- 
der, between  the  cap  and  bursting-charge. 


FIREWORKS  FOR  SIGNALS. 

The  preparations  employed  for  signals  are  rockets  and 
blue-lights. 

376.  Signal  rockets.  The  principal  parts  of  a  signal 
rocket  are  the  case  (a),  the  composition  (£),  the  pot  (c), 
the  decorations  (e)y  and  the  stick  (/). 


Fig.   128. 

Case.  The  case  is  made  by  rolling  stout  paper  covered 
on  one  side  with  paste,  around  a  former,  and  at  the 
same  time  applying  a  pressure  until  all  the  layers  adhere 
to  each  other.  The  vent  is  formed  by  choking  one  end 
of  the  case,  and  wrapping  it  with  twine.  When  the 
case  is  trimmed  and  dried,  it  is  ready  for  driving  the 
composition. 

Composition.  A  variety  of  compositions  are  employed 
for  signal  rockets ;  the  best  can  only  be  determined  by 
trial,  as  it  varies  with  the  condition  of  the  ingredients. 
The  following  proportions  are  used  at  the  West  Point 
laboratory : 


SIGNAL    SOCKETS. 


367 


NITRE. 

SULPHUR. 

CHARCOAL. 

12 

2 

3 

to  increase  the  length  and  brilliancy  of  the  trail,  add 
steel,  or  cast-iron  filings. 

Driving.  The  case  is  placed  in  a  copper  mould  which 
has  a  conical  spindle  attached  to  the  centre  of  its  base, 
to  form  the  bore ;  the  composition  is  driven  with  twenty- 
one  blows  of  the  mallet.  The  first  and  second  drifts  are 
made  hollow  to  fit  over  the  spindle,  and  the  third  is 
solid.  The  top  of  the  case  is  closed  by  moist  plaster  of 
Paris,  which  is  one  diameter  thick,  and  perforated  with 
a  hole  for  the  passage  of  the  flame  from  the  burning 
composition  to  the  pot.  The  rocket  is  primed  by  insert- 
ing a  strand  of  quick-match  into  the  bore,  after  which 
it  is  coiled  up,  and  covered  with  a  paper  cap,  until  re- 
quired for  use. 

Pot.  The  pot  is  formed  of  a  paper  cylinder  slipped 
over,  and  pasted  to  the  top  of  the  case  ;  it  is  surmounted 
with  a  paper  cone,  filled  with  tow.  The  object  of  the 
pot  is  to  contain  the  decorations  which  are  scattered 
through  the  air  by  the  explosion  which  takes  place 
when  the  rocket  reaches  the  summit  of  its  trajectory ; 
the  explosion  is  produced  by  a  small  charge  of  mealed 
powder. 

Decorations.  The  decorations  of  rockets  are  stars, 
serpents,  marrons,  gold  rain,  rain  of  fire,  &c. 

Stars.  Stars  are  formed  by  driving  the  composition, 
moistened  with  alcohol  and  gum-arabic  in  solution,  in 


368 


PYEOTECHNY. FIEE-WOEKS    FOE   SIGNALS. 


port-fire  moulds.   It  is  then  cut  into  lengths  about  f  in., 
and  dredged  with  mealed  powder. 

White. 


NITRE. 

SULPHUR. 

MEALED    POWDER. 

7 

3 

2 

Red. 


CHLOKATE    OF 
POTASSA. 

SULPHUR. 

LAMPBLACK. 

NITRATE     OF 
STRONTIA. 

7 

4 

1 

12 

Blue. 


CHLORATE    OF    POTASSA. 

SULPHUR. 

1 

AMMONIACAL     SULPHATE 
OF    COPPER. 

3 

1 

1 

Yellow. 


1 

CHLORATE    OF 
POTASSA. 

SULPHUR. 

SULPHATE     OF 
STRONTIA. 

BICARBONATE 
OF    SODA. 

4 

2 

1 

1 

Serpents.  The  case  of  a  serpent  is  similar  to  that 
of  a  rocket,  but  the  interior  diameter  is  only  0.4  inch. 
The  composition  is  driven  in,  and  the  top  is  closed  with 
moist  plaster  of  Paris.    It  is  primed  by  inserting  a  small 


BLUE-LIGHT. 


369 


piece  of  quick-match  through  the  vent ;  it  may  be  made 
to  explode  by  driving  mealed  powder  over  the  composi- 
tion.    The  composition  is — 


NITRE. 

SULPHUR. 

MEALED    POWDER. 

CHARCOAL. 

3 

3 

16 

1 
2 

Marrons.  Marrons  are  small  paper  shells,  or  cubes, 
filled  with  grained  powder,  and  primed  with  a  short 
piece  of  quick-match,  which  is  inserted  in  a  hole  punc- 
tured in  one  of  the  corners.  To  increase  the  resistance 
of  the  shell,  it  is  wrapped  with  twine,  and  dipped  in 
hit  composition. 

Stick.  The  stick  is  a  tapering  piece  of  pine,  about 
nine  times  the  length  of  the  case,  and  is  tied  to  the  side 
of  the  case  to  guide  the  rocket  in  its  flight.  The  posi- 
tion of  the  centre  of  gravity  depends  on  the  diameter  of 
the  case ;  for  a  2-in.  rocket  it  should  be  2^  in.  in  rear  of 
the  vent;  and  it  is  verified  by  balancing  on  a  knife- 
edge.  The  prescribed  dimensions  of  the  stick  should 
be  observed,  for,  if  the  stick  be  too  heavy,  the  rocket 
will  not  rise  to  a  proper  height ;  if  it  be  too  light,  it 
will  not  rise  vertically. 

37  7.  Bine-light,  A  very  brilliant  bluish  light  may  be 
made  of  the  following  ingredients,  viz. : 


NITRE. 

SULPHUR. 

REALGAR. 

1 

MEALED  POWDER. 

14 

3.7 

1 

1 

The  brilliancy  depends  on  the  purity  and  thorough 

24 


370 


PYROTECHNY. INCENDIARY    FIREWORKS. 


incorporation  of  the  ingredients.  The  composition  may 
be  driven  in  a  paper  case,  and  afterward  cut  off  to  suit 
the  required  time  of  burning.  Both  ends  of  the  case  are 
closed  with  paper  caps,  and  primed  with  quick-match, 
in  order  that  one  or  both  ends  may  be  lighted  at  pleas- 
ure. A  light  in  which  the  composition  is  1.5  inches 
diameter  can  be  easily  distinguished  at  the  distance  of 
15  miles. 


INCENDIARY  FIREWORKS. 

Incendiary  preparations  are  fire-stone,  carcasses,  incen- 
diary-match, and  hot  shot 

378.  Firestone.  Fire-stone  is  a  composition  that 
burns  slowly,  but  intensely;  it  is  placed  in  a  shell, 
along  with  the  bursting-charge,  for  the  purpose  of  set- 
ting fire  to  ships,  buildings,  &c. 

Composition.     It  is  composed  of — 


NITRE. 

SULPHUR. 

ANTIMONY. 

I 
ROSIN. 

10 

4 

1 

3 

Preparation.  In  a  furnace  of  the  second  kind,  or  in. 
a  kettle  in  the  open  air,  melt  together  one  part  of  mut- 
ton tallow  and  one  part  of  turpentine  /  the  composition, 
having  been  properly  pulverized  and  mixed,  is  added  to 
the  melted  tallow  and  turpentine,  in  small  quantities. 
Each  portion  of  the  composition  should  be  well  stirred 
with  long  wooden  spatulas  to  prevent  it  from  taking 
fire,  and  each  portion  should  be  melted  before  another 
is  added. 


CARCASS.  371 

How  used.  When  fire-stone  is  to  be  used  in  shells, 
it  is  cast  into  cylindrical  moulds,  made  by  rolling 
rocket-paper  around  a  former,  and  securing  it  with 
glue.  A  small  hole  is  formed  in  the  composition  by 
placing  a  paper  tube  in  the  centre  of  each 
mould  (a,  Hg.  129).  When  the  melted 
composition  has  become  hard,  this  hole  is 

Fig.  129.  filled  with  a  priming  of  fuze  composition, 
driven  as  in  the  case  of  a  fuze.  The  object  of  this 
priming  is  to  insure  the  ignition  of  the  fire-stone  by  the 
flame  of  the  bursting  charge. 

There  are  two  sizes  of  moulds,  the  largest  for  shells 
above  the  8-in.,  and  the  other  for  the  8-in.  and  all 
below  it. 

379.  Carcass.  A  carcass  is  a  hollow  cast-iron  projec- 
tile filled  with  burning  composition,  the  flame  of  which 
issues  through  four  fuze-holes,  to  set  fire  to  combustible 
objects. 

Composition.  The  composition  is  the  same  as  for  port- 
fires, mixed  with  a  small  quantity  of  finely-chopped  tow, 
and  as  much  white  turpentine  and  spirits  of  turpentine 
as  will  give  it  a  compressible  consistency. 

Preparation.  The  composition  is  compactly  pressed 
into  the  carcass  with  a  drift,  so  as  to  fill  it  entirely. 
Sticks  of  wood  0.5  in.  diameter  are  then  inserted  into 
each  fuze-hole,  with  the  points  touching  at  the  centre, 
so  that  when  withdrawn  corresponding  holes  shall  re- 
main in  the  composition.  In  each  hole,  thus  formed, 
three  strands  of  quick-match  are  inserted,  and  held  in 
place  by  dry  port-fire  composition,  which  is  pressed 
around  them.  About  three  inches  of  the  quick-match 
hangs  out  when  the  carcass  is  inserted  in  the  piece ;  pre- 


372  PYROTECHNY. FIREWORKS    EOR    LIGHT. 

viously  to  that,  it  is  coiled  up  in  the  fuze-hole,  and  closed 
with  a  patch  of  cloth  dipped  in  melted  kit. 

A  common  shell  may  be  loaded  as  a  carcass  by  placing 
the  bursting-charge  on  the  bottom  of  the  cavity,  and 
covering  it  with  carcass  composition,  driven  in  until  the 
shell  is  nearly  full,  and  then  inserting  four  or  five  strands 
of  quick-match,  secured  by  driving  more  composition. 
This  projectile,  after  burning  as  a  carcass,  explodes  as  a 
shell. 

380.  incendiary  match.  Incendiary  match  is  made 
by  boiling  slow-match  in  a  saturated  solution  of  nitre ; 
drying  it ;  cutting  it  into  pieces,  and  plunging  it  into 
melted  fire-stone.    It  is  principally  used  in  loaded  shells. 

381.  Hotshot.  For  the  purpose  of  setting  fire  to 
wooden  vessels,  buildings,  &c,  solid  shot  are  heated  in 
a  furnace,  before  firing,  to  a  red  heat.*  The  time  required 
to  heat  a  42-pdr.  shot  to  a  red  heat  is  about  half  an 
hour.  The  precautions  to  be  observed  in  loading  hot 
shot  are,  that  the  cartridge  be  perfectly  tight,  so  that  the 
powder  shall  not  scatter  along  the  bore,  and  that  a  wad 
of  pure  clay,  or  hay,  soaked  in  water,  be  interposed  be- 
tween the  cartridge  and  the  shot.  When  properly 
loaded,  the  shot  may  be  allowed  to  cool  without  igniting 
the  charge. 

FIREWORKS  FOR  LIGHT. 

The  preparations  for  producing  light  are  fire-balls, 
light-balls,  tarred  links,  pitched  fascines,  and  torches. 

*  In  the  British  sea-coast  service  shells  are  used  for  incendiary  purposes  by  fill- 
ing them  with  molten  iron  drawn  from  a  small  cupola  furnace.  If  the  shell  be 
broken  on  striking,  the  hot  iron  is  scattered  about ;  if  it  be  not  broken,  the  heat  pene- 
trates through  the  shell  with  sufficient  intensity  to  set  wood  on  fire. 


FIRE-BALL. 


373 


382.  Fire-ball.  A  fire-ball  is  an  oval-shaped  canvas 
sack,  filled  with  combustible  composition 
(fig.  130).  It  is  intended  to  be  thrown 
from  a  mortar  to  light  np  the  works  of 
an  enemy,  and  is  loaded  with  a  shell  to 
prevent  it  from  being  approached  and  ex- 
tinguished. 

Sack.  The  sack  is  made  of  sail-cloth, 
cut  into  three  oval  pieces  or  gores,  and 
sewed  together  at  their  edges.  Several  thicknesses  of 
cloth  may  be  used,  if  necessary.  One  end  of  the  sack  is 
left  open,  and,  after  being  sewed,  it  is  turned  to  bring 
the  seam  on  the  inside. 

Composition.     The  composition  for  a  fire-ball  consists 
of— 


Fig.  130. 


NITRE. 

SULPHUR. 

ANTIMONY. 

* 

8 

2 

1 

After  being  pulverized,  mixed,  and  sifted,  the  compo- 
sition is  moistened  with  one-thirtieth  of  its  weight  of 
water,  and  again  passed  through  a  coarse  sieve.  The 
ball  is  filled  by  pouring  a  layer  of  composition  into  the 
sack,  and  placing  the  shell  (fuze  down)  upon  it ;  after 
this,  the  composition  is  well  rammed  around  and  above 
the  shell,  and  the  sack  is  closed  at  the  top. 

Finishing.  The  bottom  of  the  sack  is  protected  from 
the  force  of  the  charge  by  an  iron  cup  (a),  called  a  culot, 
and  the  whole  is  covered  and  strengthened  with  a  net- 
work of  spun-yarn,  or  wire,  and  then  overlaid  with  a 
composition  of  pitch,  rosin,  <fcc.      * 


374  PYEOTECHNY. FIEEWOEKS    FOE    LIGHT. 

A  fire-ball  is  primed  by  driving  into  the  top  of  the 
composition  a  greased  wooden  pin  about  three  inches 
deep,  and  filling  the  hole  thus  formed  with  fuze  com- 
position, driven  as  in  a  fuze ;  space  is  left  at  the  top  of 
each  hole  for  two  strands  of  quick-match,  which  are 
fastened  by  driving  the  composition  upon  them.  The 
fuze-hole  is  covered  with  a  patch  saturated  with  kit 
composition,  which  is  a  mixture  of  rosin,  beeswax,  pitch, 
and  tallow.        ^ 

383.  Light-bail.  Light-balls  are  made  in  the  same 
manner  as  fire-balls,  except  that,  being  used  to  light  up 
our  own  works,  the  shell  is  omitted. 

384.  Tarred  links.  Tarred  links  are  used  for  lighting 
up  a  rampart,  defile,  <fcc,  or  for  incendiary  purposes. 
They  consist  of  coils  of  soft  rope,  placed  on  top  of  each 
other,  and  loosely  tied  together ;  the  exterior  diameter 
of  the  coil  is  6  inches,  and  the  interior  3  inches.  They 
are  immersed  for  about  ten  minutes  in  a  composition  of 
20  parts  oi  pitch,  and  one  of  tallow,  and  then  shaped  under 
water ;  when  dry,  they  are  plunged  in  a  composition  of 
equal  parts  of  pitch  and  rosin,  and  rolled  in  tow  or  saw- 
dust. To  prevent  the  composition  from  sticking  to  the 
hands,  they  should  be  previously  covered  with  linseed 
oil. 

How  used.  Two  links  are  put  into  a  rampart  grate, 
separated  by  shavings.  They  burn  one  hour  in  calm 
weather,  and  half  an  hour  in  a  high  wind,  and  are  not 
extinguished  by  rain.  To  light  up  a  defile,  the  links 
are  placed  about  250  feet  apart;  to  light  up  a  march, 
the  men  who  carry  the  grates  should  be  placed  to  the 
leeward  of  the  column,  and  about  300  feet  apart. 

385.  Pitched  fascines.  Fagots  of  vine-twigs,  or  other 


TOKCHES. 


375 


very  combustible  wood,  about  20  in.  long  and  4  in.  diam- 
eter, tied  in  three  places  with  iron  wire,  may  be  treated 
in  the  same  manner,  and  used  for  the  same  purposes  as 
links.  The  incendiary  properties  of  pitched  fascines 
may  be  increased  by  dipping  the  ends  in  melted  rock- 
fire;  when  used  for  this  purpose,  they  are  placed  in 
piles  intermingled  with  shavings,  quick-match,  bits  of 
port-fires,  &c,  in  order  that  the  whole  may  take  fire  at 
once. 

386.  Torches.  A  torch  is  a  ball  of  rope  impregnated 
with  an  inflammable  composition,  and  is  fastened  to  the 
end  of  a  stick,  which  is  carried  in  the  hand. 

Preparation.  Old  rope,  or  slow-match,  well  beaten 
and  untwisted,  is  boiled  in  a  solution  of  equal  parts  of 
water  and  nitre;  after  it  is  dry,  tie  three  or  four  pieces 
(each  four  feet  long)  around  the  end  of  a  pine  stick, 
about  two  inches  diameter,  and  four  feet  long ;  cover 
the  whole  with  a  mixture  of  equal  parts  of  sulphur  and 
mealed  powder,  moistened  with  brandy,  and  fill  the 
intervals  between  the  cords  with  a  paste  of  three  parts 
of  sulphur  and  one  of  quicklime.  When  it  is  dry, 
cover  the  whole  with  the  following  composition : 


PITCH. 

VENICE   TURPENTINE. 

TURPENTINE. 

3 

3 

1 
2 

How  used.  Torches  are  lighted  at  the  top,  which  is 
cracked  with  a  mallet;  they  burn  from  one  and  a  quar- 
ter to  two  hours.  In  lighting  the  march  of  a  column, 
the  men  who  carry  torches  should  be  about  100  feet 
apart. 


376        PYROTECHNY. — OFFENSIVE.    ETC.,    FIREWORKS 


OFFENSIVE  AND   DEFENSIVE  FIEEWOKKS. 

The  principal  preparations  of  this  class,  employed  in 
modern  warfare,  are  bags  of  powder  and  light-barrels. 

387.  Bag§  of  powder.  Bags  or  cases  of  powder  may 
be  used  to  blow  down  gates,  stockades,  or  form  breaches 
in  thin  walls.  The  petard  was  formerly  employed  for 
these  purposes,  but  it 'is  now  generally  thrown  aside. 

From  trials  made  in  England,  it  has  been  shown  that 
a  sand-bag  (covered  with  tar,  and  sanded  to  prevent  it 
from  sticking)  containing  50  lbs.  of  powder,  has,  suffi- 
cient force  to  blow  down  a  gate  formed  of  4-inch  oak 
scantling,  and  supported  by  posts  10  inches  in  diameter, 
and  8  feet  apart;  and  a  bag  containing  60  lbs.  of  pow- 
der, and  weighted  with  two  or  three  bags  of  earth,  has 
sufficient  force  to  make  a  large  hole  in  a  14-inch  brick 
wall.  The  effect  of  the  explosion  may  be  much  in- 
creased by  making  three  sides  of  the  bag  with  leather, 
and  the  fourth  of  canvas,  which  should  rest  against 
the  object.  A  suitable  means  of  exploding  bags  of 
powder  is  a  time-fuze,  or  the  ordinary  safety -fuze  for 
blasting  rocks. 

388.  JLight-harrei.  A  light-barrel  is  a  common  pow- 
der-barrel pierced  with  numerous  holes,  and  filled  with 
shavings  that  have  been  soaked  in  a  composition  of 
pitch  and  rosin;  it  serves  to  light  up  a  breach,  or  the 
bottom  of  a  ditch. 


OENAMENTAL  FIREWORKS. 
389.  Object,  &c.  Ornamental  fireworks  are  employed 


GERBE.  377 

to  celebrate  great  events,  as  victories,  treaties  of  peace, 
funerals,  <fcc.  They  are  divided  into  fixed  pieces,  mov- 
able pieces,  decorative  pieces,  and  preparations  for  com- 
municating fire  from  one  part  of  a  piece  to  another. 
The  different  effects  are  produced  by  modifying  the  pro- 
portions of  the  ingredients  of  the  burning  composition, 
so  as  to  quicken  or  retard  combustion,  or  by  introducing 
substances  that  give  color  and  brilliancy  to  the  flame. 
The  fixed  pieces  are  lances,  petards,  gerbes,  flames,  &c. 

390.  i^ance.  Lances  are  small  paper  tubes  from  0.2 
to  0.4  in.  diameter,  filled  with  a  composition  which  emits 
a  brilliant  light  in  burning 
(a,  fig.  131).  Instead  of  a  sin- 
gle composition,  each  lance 
may  contain  two  or  more  Fig.  isl 
compositions,  which,  in  turn,  emit  different-colored 
flames.  The  case  should  be  as  thin  as  possible,  in  order 
that  the  color  of  the  flame  of  the  composition  may  not 
be  affected  by  that  of  the  paper.  Lances  are  generally 
employed  to  form  figures;  this  is  done  by  dipping  one 
end  in  glue,  and  sticking  them  in  holes  arranged  after 
a  certain  design,  in  a  piece  of  wood- work. 

391.  Petard.  Petards  are  small  paper  cartridges  filled 
with  powder.  One  end  is  entirely  choked,  and  the 
other  is  left  partially  open  for  the  passage  of  a  strand 
of  quick-match,  destined  to  set  fire  to  the  powder. 

A  petard  is  usually  placed  at  the  fixed  end  of  a  lance, 
that  the  flame  may  terminate  with  an  explosion  (b,  fig. 
131)  ;  they  are  also  used  to  imitate  the  fire  of  mus- 
ketry. 

392.  Oerbe.  Gerbes  are  strong  paper  tubes  or  cases, 
filled  with  a  burning  composition.     The  ends  are  tamped 


378 


PYKOTECHNY. MOVABLE     PIECES. 


with  moist  plaster  of  Paris  or  clay;  through  one,  a  hole 
is  bored,  extending  a  short  distance  into  the  composi- 
tion, that  it  may  emit  a  long  sheaf  or  gerbe  of  brilliant 
sparks. 

The  diameter  of  the  case  is  about  one  inch,  and  the 
length  depends  upon  the  required  time  of  burning. 
The  number  of  blows  to  each  ladleful  of  composition 
is  ten. 

Gerbes  are  secured  to  the  frame  of  the  piece  with  wire 
or  strong  twine,  and  pointed  in  the  direction  that  the 
flame  is  to  take. 

Composition. 


MEALED  POWDER. 

NITRE. 

SULPHUR. 

CAST-IRON    FILINGS 
MIXED    WITH    SULPHUR. 

32 

16 

10 

26.4 

393.  Flame.  Flames  consist  of  lance  or  star  compo- 
sition, driven  into  paper  cases  or  earthen  vases.  The 
diameter  of  the  burning  surface  should  be  large,  to  give 
intensity  to  the  flame.  Lance  composition  is  driven 
dry,  and  with  slight  pressure.  Star  composition  should 
be  moistened,  and  driven  with  greater  pressure  than  the 
preceding. 

MOVABLE  PIECES. 

The  movable  pieces  are  shy -rockets,  tourbillions,saxons, 
jets,  Roman  candles,  paper  shells,  &c. 

394.  Sky-rocket.  Sky-rockets  are  the  same  as  the 
signal-rockets  before  described,    except  that  the  com- 


JETS. 


379 


position  is  arranged  to  give  out  a  more  brilliant  train 
of  fire. 

Composition. 


MEALED    POWDER. 

NITRE. 

SULPHUR. 

CAST-IRON    FILINGS. 

122 

80 

40 

40 

395.  Tourbiiiion.  The  tourbillion  is  a  case  filled  with 
sky-rocket  composition,  and  which  moves  with  an  up- 
ward spiral  motion.  The  spiral  motion  is  produced  by 
six  holes — two  lateral  holes  (one  on  each  side),  for  the 
rotary  motion,  and  four  on  the  under  side,  for  the  up- 
ward motion.  It  is  steadied  by  two  wings  formed  by 
attaching  a  piece  of  a  hoop  to  the  middle  of  the  case, 
and  at  right  angles  to  its  length. 

To  give  it  a  proper  initial  direction,  a  hole  is  made 
through  the  centre  of  the  case  to  fit  on  a  vertical  spin- 
dle, which  is  fastened  to  an  upright  post. 

396.  Saxon.  The  saxon  is  the  same  as  the  tour- 
billion,  except  that  it  is  only  pierced  with  the  central 
and  two  lateral  holes,  and  has  no  wings.  The  central 
hole  is  placed  on  a  horizontal  spindle,  and  the  piece  has 
the  appearance  of  a  revolving  sun. 

397.  Jet§.  Jets  are  rocket-cases  filled  with  a  burning 
composition  ;  they  are  attached  to  the  circumference  of 
a  wheel,  or  the  end  of  a  movable  arm,  to  set  it  in 
motion.  They  also  produce  the  effect  of  gerbes  ;  and  to 
increase  the  circle  of  fire,  they  are  inclined  to  the  radius 
at  an  angle  of  20°  or  30°. 


380  PYROTECHNY. MOVABLE    PIECES. 

Com/position. 


MEALED    POWDER. 

NITRE. 

SULPHUR. 

CAST-IRON    FILINGS. 

50 

36.5 

15 

24.6 

398.  Roman  candle*.  A  Roman  candle  is  a  strong 
paper  tube  containing  stars,  which  are  successively 
thrown  out  by  a  small  charge  of  powder  placed  under 
each  star.  A  slow-burning  composition  is  placed  over 
each  star  to  prevent  all  of  them  from  taking  fire  at 
once. 

Slow  Composition. 


MEALED    POWDER. 

CHARCOAL. 

2 

1 

399.  Paper  shell.  This  piece  is  a  paper  shell  filled 
with  decorative  pieces,  and  fired  from  a  common  mortar. 
It  contains  a  small  bursting-charge  of  powder,  and  has 
a  fuze  regulated  to  ignite  it  when  the  shell  reaches  the 
summit  of  its  trajectory. 

The  shell  is  made  by  pasting  several  layers  of  thick 
paper  over  a  sphere  of  wood,  cutting  the  covering  thus 
formed  in  halves,  so  as  to  remove  the  sphere,  joining  the 
halves  again,  and  pasting  paper  over  them  until  the 
thickness  is  sufficient  to  resist  the  charge  of  the  mortar. 

400.  Decorative  pieces.  Decorative  pieces  are  stars, 
serpents,  marrons,  &c,  described  under  the  head  of 
rockets.     . 

401.  For  communicating  fire.     Preparations  for  com- 


GENEKAL    KEMAKK.  381 

municating  fire  from  one  piece  to  another  are  quick- 
match,  leaders,  port-fires,  and  mortar-fuzes. 

The  leader  is  a  thin  paper  tube  containing  a  strand 
of  quick-match,  and  it  is  united  to  a  piece  by  pasting 
pieces  of  paper  over  the  joint.  If  the  piece  is  to  be  fired 
at  once,  the  leader  may  be  omitted,  and  strands  of  quick- 
match  tied  together  used  in  its  place. 

402.  General  remark.  The  foregoing  pieces  are  gen- 
erally mounted  on  pieces  or  frames  of  light  wood,  and 
are  susceptible  of  being  combined  so  as  to  produce  a 
great  variety  of  striking  effects. 


a 


382  SCIENCE   OF    GUNNERY. 


PART   II 


CHAPTER   VIII. 
SCIENCE  OF  GUNNERY. 

The  science  of  gunnery  treats  of  the  motion  of  pro- 
jectiles, and  of  their  effects.  Ballistics  is  that  branch 
of  the  science  of  gunnery  which  treats  of  the  motion  of 
projectiles. 

403.  History  of  ballistic*.  Ancient  artillerists  consid- 
ered that  the  trajectory,  or  path  described  by  a  projec- 
tile after  it  left  its  piece,  was  composed  of  three  distinct 
parts: — 1st.  The  violent,  which  approached  a  straight 
line.  2d.  The  middle,  or  mixed,  which  was  a  circle.  3d. 
The  last,  or  natural,  which  was  also  a  right  line. 

Tartaglia,  an  Italian  engineer,  invented  the  quadrant 
for  measuring  elevations,  which  he  divided  into  twelve 
parts,  and  by  which  he  was  able  to  compare  the  ranges 
of  different  cannon,  fired  under  the  same  or  different 
degrees  of  elevation.  He  demonstrated  that  no  portion 
of  the  trajectory  was  a  right  line,  and  that  the  angle 
which  gave  the  greatest  range  was  45°. 

Galileo.  About  "£$#%  Galileo  discovered  the  laws 
which  govern  the  fall  of  bodies,  and  from  these  he  dem- 
onstrated that  the  curve  described  by  a  projectile, 
thrown  in  a  direction  oblique  to  the  horizon,  is  a  pa- 
rabola, the  axis  of  which  is  vertical.     He  did  not  con- 


FUNDAMENTAL    QUESTIONS.  383 

sider  that  the  air  offered  any  material  resistance  to  the 
motion  of  artillery  projectiles. 

Newton.  About  1723,  Newton  demonstrated  that  the 
curve  described  by  a  spherical  projectile  in  the  air,  was 
far  from  being  a  parabola;  that  the  two  branches  were 
dissimilar,  and  that  the  descending  branch  would  be- 
come vertical  if  sufficiently  prolonged.  While  he  con- 
sidered the  resistance  of  the  air  proportioned  to  the 
square  of  the  velocity,  he  did  not  conceal  the  fact  that 
this  was  but  an  approximation  to  the  true  relation, 
which  remained  to  be  determined  by  experiment. 

Robins.  About  1765,  Robins  invented  an  instrument 
for  determining  the  initial  velocity  of  a  projectile,  called 
the  ballistic  pendulum,  by  which  he  was  able  to  show 
that  the  range  in  vacuo  was  much  greater  than  in  air. 
He  also  discovered  that  the  rotary  motion  which  spher- 
ical projectiles  generally  assume  around  their  centres 
of  gravity,  will  cause  them  to  deviate  from  their  true 
direction. 

Tlutton.  Hutton,  who  lived  about  the  beginning  of 
the  present  century,  improved  the  ballistic  pendulum, 
and  applied  it  to  determine  the  true  law  of  the  resist- 
ance of  the  air,  as  exemplified  in  projectiles  of  small 
calibre. 

At  Metz,  in  1839  and  '40,  further  experiments  were 
made  on  the  resistance  of  the  air  to  projectiles  of  large 
size,  moving  with  high  velocities,  and  the  law  of  varia- 
tion was  determined  with  great  accuracy. 

INITIAL   VELOCITY. 

404.      Fundamental  questions     The  subject  of  ballis- 


384  SCIENCE    OF    GUNNERY. INITIAL    VELOCITY. 

tics  presents  two  fundamental  questions  :  1st.  To  deter- 
mine the  initial  velocity  of  a  projectile  for  a  known 
piece  and  charge  of  powder.  2d.  Knowing  the  initial 
velocity  and  angle  of  projection,  to  determine  the  range, 
time  of  flight,  remaining  velocity,  and,  in  fact,  all  the 
circumstances  of  the  projectile's  motion. 

405.  Definition  of  velocities  The  velocity  of  a  pro- 
jectile, at  any  point  of  its  flight,  is  the  space  in  feet, 
passed  over  in  a  second  of  time,  with  a  continuous,  uni- 
form motion.  Initial  velocity  is  the  velocity  at  the 
muzzle  of  the  piece ;  remaining  velocity  is  the  velocity 
at  any  point  of  the  flight ;  terminal  velocity  is  the  ve- 
locity with  which  it  strikes  its  object ;  Midi  final  velocity 
of  descent  in  air,  is  the  uniform  velocity  with  which  a 
projectile  moves,  when  the  resistance  of  the  air  becomes 
equal  to  the  accelerating  force  of  gravity. 

The  initial  velocity  of  a  projectile  may  be  determined 
by  the  principles  of  mechanics  which  govern  the  action 
of  the  powder,  the  resistance  of  the  projectile,  &c,  or  by 
direct  experiment. 

406.  By  mechanical  principles  The  instant  that 
the  charge  of  a  fire-arm  is  converted  into  gas,  it  exerts 
an  expansive  effort  which  acts  to  drive  the  projectile 
out  of  the  bore.  If  the  gaseous  mass  be  divided  into 
elementary  sections  perpendicular  to  its  length,  it  will 
be  seen  that,  in  their  efforts  to  expand,  each  section  has 
not  only  to  overcome  its  own  inertia,  but  the  inertia  of 
the  piece  and  projectile,  as  well  as  the  inertia  of  the  sec- 
tions which  precede  it.  The  tension  of  each  section, 
therefore,  increases  from  the  extremities  of  the  charge  to 
some  intermediate  point  where  it  is  a  maximum.  The 
pressure  on  all  sides  of  the  section  of  maximum  density 


PRACTICAL    RULE   TOR    INITIAL    VELOCITY.  385 

being  equal,  it  will  remain  at  rest,  while  all  the  others 
will  move  in  opposite  directions,  constantly  pressing 
against  the  projectile  and  piece,  and  accelerating  their 
velocities. 

As  the  projectile  moves  in  the  bore,  the  space,  in 
which  the  gases  expand  is  increased,  while  their  density 
is  diminished  ;  it  follows  that  the  force  which  sets  a  pro- 
jectile in  motion  in  a  fire-arm  varies  from  several  causes ; 
1st.  It  varies  as  the  space  behind  the  projectile  increases, 
or  as  the  velocity  regarded  as  a  function  of  the  time ; 
2d.  It  varies  throughout  the  column  of  gas  for  the  same 
instant  of  time ;  and  3d.  It  varies  from  the  increasing 
quantities  of  gas  developed  in  the  successive  instants  of 
the  combustion  of  the  powder. 

Piobert  has  made  the  movement  of  a  projectile  in  a 
fire-arm  the  subject  of  a  very  elaborate  analytical  inves- 
tigation, based  on  the  mechanical  principles  of  the  con- 
servation of  the  motion  of  the  centre  of  gravity,  living 
forces,  and  Rumford's  formula  for  the  relation  between 
the  density  and  pressure  of  fired  gunpowder. 

Formula  for  initial  velocity.  By  supposing  the  weight 
of  the  projectile  to  be  nothing,  compared  to  that  of  the 
piece  and  carriage  combined,  that  the  tension  of  the 
gases  is  proportional  to  the  density,  that  the  length  of 
the  bore  is  sufficient  for  the  entire  charge  to  be  con- 
verted into  gas,  and  that  the  projectile  has  no  windage, 
the  complicated  equations  of  Piobert  may  be  reduced  to 


V—Xx log — ; 


in  which  F"is  the  initial  velocity,  X  a  constant  to  be  de- 
termined by  experiment,  m  the  weight  of  the  powder,  p 


386  SCIENCE    OF    GUNNEKY. INITIAL    VELOCITY. 

the  weight  of  the  projectile,  and  M  the  weight  of  pow- 
der (loose)  which  would  fill  the  bore. 

The  above  value  of  V  should  be  diminished  for  the 
loss  arising  from  windage ;  the  loss  of  force  from  wind- 
age is  directly  proportional  to  the  space  between  the 
bore  and  projectile,  and  inversely-  as  the  area  of  the 
bore.     Hence  we  have 

C*-B2 

in  which  A  is  a  constant  to  be  determined  by  experi- 
ment, C  is  the  radius  of  the  bore,  and  H  the  radius  of 
the  projectile.  For  ordinary  windage  this  may  be  re- 
placed by 

in  which  W  is  the  windage,  and  the  general  expression 
for  the  initial  velocity  becomes 


There  are  three  unknown  quantities  in  this  equation ; 
V,  A,  and  a  ;  V  can  be  determined  by  direct  experi- 
ment for  two  or  more  charges  of  powder,  and  projectiles, 
giving  two  equations  containing  the  remaining  unknown 
quantities  x  and  a.  According  to  the  experiments  made 
at  the  Washington  arsenal  with  the  ballistic  pendulum, 
the  mean  values  of  the  co-eificients  X  and  a,  for  Dupont's 
powder  in  guns  of  various  calibres  (from  6-pdr.  to  32-pdr.) 
are:  X =3500  feet,  and  A  =  3200  feet. 

M  is  equal  to  the  gravimetric  density  of  the  powder 
(referred  to  pounds  and  inches)  multiplied  by  the  vol- 
ume of  the  bore. 


WHAT   AFFECTS    INITIAL    VELOCITY. 


387 


Example.  What  is  the  initial  velocity  of  a  6-pdr.  shot  fired  with 
a  service-charge  ? 

m=1.25  lbs. ;  p=6.25  lbs. ;  (7=1.83  in  ;  W=.09  in. ;  length  of 
bore,  57.5  in.;  weight  of  a  cubic  inch  of  powder,  0.0293  lbs. 

/      1.25  17.82  .09 

F=3500  V  ftai+ii-  log-r25-3200r^=1444- ft- 

The  mean  of  11  fires  with  the  6-pdr.  gun  pendulum  at  West 
Point,  in  November,  1860,  was  1436.5  feet. 

407.  Practical  rule  for  initial  velocity.  For  the  ordi- 
nary purposes  of  practice,  where  the  weight  of  the 
powder  and  projectile  alone  vary,  initial  velocities  may 
be  considered  as  directly  proportional  to  the  square  root 
of  the  weight  of  powder  divided  by  the  square  root  of  the 
weight  of  the  projectile  ;  or 

V     •    V  /.    •      . •        . .,    V   V  .      . 

V  m   Vm!  Vp    rm 

When  V  is  known  for  a  given  charge  of  powder  p'  and 
projectile  m',  the  value  of  V  can  be  obtained  for  any 
other  charge  of  powder,  py  and  projectile,  m,  of  the  same 
calibre.  This  law  however  only  holds  true  within  cer- 
tain limits,  or  when  the  powder  is  completely  consumed 
before  the  projectile  leaves  the  piece.* 

408.  What   affects   initial   velocity.      The    principal 

*  Table  of  Initial  Velocities  with  service  charges. 


KIND  OF  CANNON. 


6-pdr.  field, 

12-pdr.     "    

12-pdr.     "    howitzer,. 

24-pdr.  siege-gun,    

8-inch  siege  howitzer, , 
32-pdr.  sea-coast  gun,. 
15-inch  columbiad 


CHARGE 

KIND  OF  PROJECTILE. 

OF 

POWDER. 

SHOT. 

SHELLS. 

sph'l  case. 

Lbs. 

Feet. 

Feet. 

Feet. 

1.25 

1439 

1357 

2.50 

1486 

1486 

1.00 

1054 

953 

6.00 

1680 

1670 

8.00 

1870 

4.00 

907 

8.00 

1640 

1450 

40.00 

1000 

Note. — "When  the  initial  velocities  of  shot,  shells,  and  spherical-case  shot  are 
given,  the  weight  of  the  charge  refers  to  the  solid  shot. 


388  SCIENCE    OF    GUNNERY. INITIAL    VELOCITY. 

causes  which  influence  initial  velocity,  are  the  character 
of  the  piece,  powder,  and  projectile.  Most  of  these  have 
been  considered  under  their  appropriate  heads,  in  treat- 
ing of  the  construction  of  cannon  ;  it  will  only  be  neces- 
sary, therefore,  to  recapitulate  them  here.  They  are 
the  size  and  position  of  the  vent,  the  windage,  the 
length  of  the  bore,  the  form  of  the  chamber,  the  diam- 
eter and  density  of  the  projectile,  the  windage  of  the 
cartridge,  and  the  form,  size,  density,  and  dryness  of 
the  grains  of  powder,  and  the  barometric,  thermometric, 
and  hygrometric  states  of  the  atmosphere. 

It  has  been  found  by  late  experiments  that  the  initial 
velocity  is  unaffected  by  the  angle  of  fire.  Theoreti- 
cally, varying  the  weight  of  the  piece  should  exert  an 
influence  on  the  initial  velocity ;  but,  in  consequence  of 
the  great  disparity  of  the  weight  of  the  piece  and  pro- 
jectile, this  influence  is  inappreciable  in  practice. 

409.  Determination  of  initial  velocity  by  experiment. 
A  great  variety  of  instruments  have  been  invented  to 
determine  directly  the  initial  velocity  of  a  projectile,  the 
most  reliable  of  which  are  the  gun-pendulum,  the  bal- 
listic  pendulum,  and  the  electro-ballistic  machines. 

In  the  first,  the  velocity  of  the  projectile  is  determined 
by  suspending  the  piece  as  a  pendulum,  and  measuring 
the  recoil  impressed  on  it  by  the  discharge ;  the  expres- 
sion for  the  velocity  is  deduced  from  the  fact,  that  the 
quantity  of  motion  communicated  to  the  pendulum  is 
equal  to  that  communicated  to  the  projectile,  charge  of 
powder,  and  the  air.  The  second  apparatus  is  a  pendu- 
lum, the  bob  of  which  is  made  strong  and  heavy,  to 
receive  the  impact  of  the  projectile;  and  the  expression 
for  the  velocity  of  the  projectile  is  deduced  from  the 


THE    WEST   POINT   BALLISTIC   MACHINE.  389 

fact,  that  the  quantity  of  motion  of  the  projectile  before 
impact  is  equal  to  that  of  the  pendulum  and  projectile 
after  impact.  These  machines  have  been  carried  to 
great  perfection,  both  in  this  country  and  France,  and 
very  accurate  and  important  results  have  been  obtained 
by. them;  but  they  are  very  expensive,  and  cannot  be 
easily  adapted  to  the  various  wants  of  the  service. 

The  employment  of  electricity  to  determine  the  veloc- 
ity of  projectiles,  was  first  suggested  by  Wheat  stone,  in 
1840.  The  application  depends  on  the  very  great  veloc- 
ity of  electricity,  which,  for  short  distances,  may  be 
considered  instantaneous.  The  general  method  of  apply- 
ing this  agent  is  by  means  of  galvanic  currents,  or  wires, 
supported  on  target  frames,  placed  in  the  path  of  the 
projectile,  and  communicating  with  a  delicate  time- 
keeper. The  successive  ruptures  of  the  wires  mark  on 
the  time-keeper  the  instant  that  the  projectile  passes 
each  wire,  and  knowing  the  distances  of  the  wires  apart, 
the  mean  velocities,  or  velocities  at  the  middle  points, 

can  be  obtained  by  the  relation,  velocity  =  -i . 

J  '  J      time 

The  various  plans  in  use  differ  only  in  the  manner 

of  recording  and  keeping  the  time  of  flight ;  one  of  the 

simplest  and  most  common  instruments  employed  is 

the  pendulum.     The  ballistic  machine  of  Captain  Navez, 

of  the  Belgian  service,  has  been  tried  in  this*  country, 

but  has  been  found  too  delicate  and  complicated  for 

general  purposes. 

*  In  consequence  of  the  variable  nature  of  the  resistance  of  the  air,  this  mean 
velocity  does  not  strictly  correspond  to  the  middle  point  between  the  targets.  The 
difference,  however,  is  very  slight,  as  is  shown  by  Captain  Navez  in  the  case  of  a 
6-pdr.  ball  moving  with  an  initial  velocity  of  600  meters,  over  a  space  of  50  meters; 
the  difference  between  the  mean  velocity  and  the  velocity  which  it  should  have  at 
the  middle  point,  is  only  0.05  meter. 


390 


SCIENCE    OF    GUNNEKY. INITIAL    VELOCITY. 


410.  The  We§t  Point  ballistic  machine.  Fig.  132 
represents  the  front  and  end  views  of  an  electro-ballistic 
machine  originally  devised  by  the  author  for  the  use  of 
the  Military  Academy,  and  since  adopted  by  the  ord- 
nance department,  for  proving  powder,  &c. 


Fig.  132. 

a  is  a  bed-plate  of  metal,  which  supports  a  graduated 
arc  (#).  This  arc  is  placed  in  a  vertical  position  by 
means  of  thumb-screws  and  spirit-levels  attached  to  it ; 
and  it  is  graduated  into  degrees  and  fifths,  commenc- 
ing at  the  lowest  point  of  the  arc,  and  ending  at  90°. 

pp'  are  two  pendulums  having  a  common  axis  of 
motion,  passing  through  the  centre,  and  perpendicular 
to  the  plane  of  the  arc.  The  bob  of  the  pendulum  p' 
is  fixed,  but  that  of  p  can  be  moved  up  and  down 
with  a  thumb-screw,  so  as  to  make  the  times  of  vibra- 
tion equal. 

m  and  m  are  two  electro-magnets  attached  to  the 
horizontal  limb  of  the  arc,  to  hold  up  the  pendulums 
when  they  are  deflected  through  angles  of  90°. 

s  and  <?'  are  pieces  of  soft  iron  attached  to  the  pro- 
longations of  the  suspension-rods,  in  such  way  as  to  be 


THE    WEST   POINT   BALLISTIC    MACHINE.  391 

in  contact  with  the  lower  poles  of  the  magnets,  when 
the  pendulums  are  deflected. 

d  is  an  apparatus  to  record  the  point  at  which  the 
pendulums  pass  each  other,  when  they  fall  by  the 
breaking  of  the  currents  which  excite  the  magnets.  It 
is  attached  to  the  prolongation  of  the  suspension-rod  p\ 
and  consists  essentially  of  a  small  pin  enclosed  in  a 
brass  tube;  the  end  of  the  pin  near  the  arc  has  a  sharp 
point,  and  the  other  is  terminated  with  a  head,  the  sur- 
face of  which  is  oblique  to  the  plane  of  the  arc.  As 
the  pendulums  pass  each  other,  a  blunt  steel  point  at- 
tached to  the  lower  extremity  of  the  suspension-rod  p, 
strikes  against  the  oblique  surface  of  the  head  of  the 
pin,  which  presses  the  point  into  a  piece  of  paper 
clamped  to  the  arc,  leaving  a  small  puncture  to  mark 
the  point  of  passage.  To  disengage  the  marking-point 
from  the  paper,  the  tube  containing  the  pin  is  free  to 
revolve  through  an  angle  of  90°,  around  a  vertical  axis, 
in  which  revolved  position  it  swings  clear  both  of  the 
paper  and  the  pendulum  p.  Tolerably  strong  paper 
should  be  used  in  recording,  to  prevent  the  point  from 
tearing  it. 

cc  and  c'c  represent  the  wires  which  conduct  the 
two  currents  that  excite  the  magnets  m  and  m.  These 
wires  terminate  in  four  clamp-screws  secured  to  the  bed- 
plate, for  the  purpose  of  attaching  the  long  wires  lead- 
ing through  the  batteries  to  the  targets. 

Targets.  The  targets  are  two  frames  of  wood  placed 
so  as  to  support  the  wires  in  a  position  to  be  cut  by  the 
projectile.  For  the  purpose  of  obtaining  the  initial  ve- 
locity, the  first  should  be  placed  about  20  feet  from  the 
muzzle  of  the  piece,  that  the  flame  may  not  break  the 


392  SCIENCE    OF    GUNNERY. INITIAL   VELOCITY. 

current  before  the  projectile  reaches  it;  the  position  of 
the  second  depends  on  the  velocity  of  the  projectile. 
For  cannon,  it  should  be  placed  about  100  feet  from  the 
first  target;  and  for  small-arm  and  mortar  projectiles, 
about  50  feet.  The  number  of  times  that  the  wire 
should  cross  the  targets  depends  on  the  size  of  the  pro- 
jectile and  the  accuracy  of  its  flight. 

Currents  and  batteries.  The  magnets  should  be  made 
of  the  purest  attainable  wrought  iron,  in  order  that 
they  shall  retain  no  magnetic  force  after  the  exciting 
currents  are  broken ;  and  for  this  purpose  they  are  best 
made  of  bundles  of  wire.  The  batteries  should  be  of 
nearly  equal  power  and  constancy,  in  order  that,  in  case 
the  magnets  do  retain  a  portion  of  their  magnetism,  the 
remaining  portion  may  be  as  uniform  as  possible. 

Grove's  or  Bunsen's  batteries  are  the  best  that  can  be 
used  for  this  purpose.  The  power  of  the  battery  is 
regulated  by  the  distance  of  the  targets  and  the  size 
of  the  conducting  wires.  If  a  weak  battery  be  used, 
the  magnetic  power  may  be  increased  by  increasing  the 
diameter  of  the  wire,  or  by  resting  pieces  of  soft  iron 
on  the  upper  poles  of  the  magnet. 

In  experimenting  with  cannon,  the  machine  should 
be  placed  about  120  yards  from  the  piece,  to  prevent 
any  disturbance  from  the  discharge;  at  this  distance 
the  record  will  have  been  made  before  the  sound  reaches 
the  machine.  For  this  distance,  three  cups,  in  which  the 
zinc  cylinders  are  8  inches  long  and  3  inches  diameter, 
and  an  insulated  copper  wire  .06"  diameter,  have  been 
found  to  answer  a  good  purpose. 

The  disjunctor.  The  disjunctor  is  a  small  auxiliary 
instrument  for  closing  and  breaking  the  currents  at  will. 


THE    WEST   POINT    BALLISTIC    MACHINE.  393 

It  affords  the  means  of  verifying  the  accuracy  of  the 
pendulum  machine  by  a  succession  of  simultaneous  rup- 
tures of  the  wires;  when  the  machine  is  in  good  condi- 
tion, the  position  of  the  point  of  meeting  seldom  varies 
a  tenth  of  a  degree,  an  error  which  corresponds  to  only 
.000154  of  a  second  of  time. 

When  the  currents  are  of  equal  strength,,  and  the 
starting  points  are  properly  adjusted,  the  point  of  meet- 
ing will  be  found  opposite  to  the  zero  of  the  grad- 
uated arc ;  if  of  unequal  intensity,  the  point  will  be 
found  near  the  zero  point  and  on  the  side  of  the 
stronger  magnet.  As  this  position  is  nearly  constant  for 
the  same  currents,  the.  error  of  the  reading  can  be  easily 
corrected.  If  the  error  be  positive,  subtract  it ;  if  nega- 
tive, add  it. 

Arrangement,  &c.  Figure  133  shows  the  working 
arrangement  of  the  several  pieces :  a  represents  the  pen- 
dulum; b  the  disjunctor;  c  c  and  &  c' 
the  currents;  e  e'  the  batteries;  and 
d  the  position  of  the  gun.  To  operate 
them,  the  disjunctor  is  closed,  the 
pendulums  are  deflected,  the  marking- 
pin  revolved  perpendicular  to  the  arc, 
the  piece  is  fired,  and  the  position  of  Fis- 133- 

the  puncture  in  the  paper,  with  reference  to  the  grad- 
uated arc,  noted. 

To  determine  the  time.  The  velocity  of  the  electric 
currents  being  considered  instantaneous,  and  the  loss  of 
power  of  the  magnets  simultaneous  with  the  rupture  of 
the  currents,  it  follows  that  each  pendulum  begins  to 
move  at  the  instant  that  the  projectile  cuts  the  wire, 
and  that  the  interval  of  time  corresponds  to  the  differ- 


394  SCIENCE    OE    GUNNERY. INITIAL    VELOCITY. 

ence  of  the  arcs  described  by  the  pendulums  up  to  the 
time  of  meeting. 

Let  m  andm',  fig.  134,  represent  the  positions  of  the 
two  magnets,  and  let  the  interval  between  the  rupture 
be  such  that  the  centres  of  oscilla- 
tion will  pass  each  other  at  i.  As 
the  times  of  vibration  are  equal,  the 
interval  of  time  will  correspond  to 
the  arc  i  i\  the  arc  rn!  i  being  equal  Fie- 13±. 

to  m  i'.  A  vertical  line  through  the  centre  of  motion 
bisects  the  arc  i  i .  The  reading  therefore  corresponds 
to  one-half  of  the  required  time,  or  time  of  passage  of 
the  projectile  between  the  wires. 

To  determine  a  formula  for  the  time  that  it  takes  for 
one  of  the  pendulums  to  pass  over  a  given  arc,  let  I  be 
the  length  of  the  equivalent  simple  pendulum,  v  the 
velocity  of  the  centre  of  oscillation  or  point  m\  y  the 
vertical  distance  passed  over  by  this  point,  x  the  vari- 
able angle  which  the  line  of  suspension  makes  with  the 
horizontal,  and  t'  the  time  necessary  for  the  point  m'  to 
pass  over  an  entire  circumference,  the  radius  of  which 
is  Z,  with  a  uniform  velocity  v,  we  have, 

v=V2gy.  . 
Substituting  for  y  its  value  in  terms  of  the  constant 
angle  of  half-oscillation  and  the  variable  angle  a?,  the 
above  expression  becomes, 

v=vl>gl  cos.  (90°— a)  ; 
from  which  we  see  that  the  velocity  of  the  pendulum 
increases  from  its  highest  to  its  lowest  point,  and  vice 
versa. 

The  time  t'  is  equal  to  the  circumference  of  the  circle, 
the  radius  of  which  is  Z,  divided  by  the  velocity,  v; 


THE    WEST   POINT   BALLISTIC    MACHINE.  395 

again  divide  this  by  360,  we  have  the  time  of  passing 
over  each  degree,  or, 

t=z 2j 

S60i/2gl  cos.(90°— 5)  • 

To  determine  £,  it  is  necessary  to  change  the  cylin- 
drical arms  of  suspension  to  knife-edges,  in  order  to  de- 
termine the  time  of  vibration  through  a  veiy  small  arc. 
The  mean  of  500  vibrations  will  be  very  near  the  exact 
time  of  a  single  vibration.  Knowing  the  time  of  a 
single  vibration,  the  length  of  the  equivalent  simple 
pendulum  can  be  obtained  by  the  relation  l=d't"*,  in 
which  t"  is  this  time,  and  V  is  the  length  of  the  simple 
second's  pendulum  at  the  place  of  observation. 

At  West  Point  Z'=:39.11448  inches. 
"  "  ^=32. 17050  feet. 

In  this  way  all  the  constants  of  the  expression  for  t 
are  known,  and  by  assigning  different  values  to  a?,  a 
table  can  be  formed,  from  which  the  times  corresponding 
to  different  arcs  can  be  obtained  by  simple  inspection. 
The  table  in  chapter  XIII.  is  calculated  for  the  West 
Point  machine.  y 

MOTION  OF  A  PROJECTILE  IN  VACUO. 

411.  Determination  of  equation§  of  motion.  A  'pro- 
jectile is  a  body  thrown  or  impelled  forward,  generally 
in  the  air ;  and  the  trajectory  is  the  line  described  by 
its  centre  of  inertia.  The  movement  of  a  projectile  will 
be  considered  firstly  in  vacuo,  and  secondly  in  the  air. 

Let  A  (fig.  135)  be  the  position  of  the  muzzle  of  a 
fire-arm,  and  the  line  A  B  its  axis  prolonged. 


396         SCIENCE   OF    GUNNERY. MOTION    IN    VACUO. 


Fig.  135. 

Let  <P  represent  the  angle  which  this  line  makes  with 
the  horizontal  plane,  or  the  angle  of  projection. 

V  the  initial  velocity. 

v  the  velocity  at  the  point  m. 

t  the  time  of  flight  to  the  same  point. 

6  the  inclination  of  the  tangent  at  this  point. 

#,  y,  the  co-ordinates  of  this  point. 

JTthe  horizontal  range. 

Y  the  greatest  height  of  ascent. 

T the  whole  time  of  flight,  or  for  the  range  X. 

If  the  projectile  were  only  acted  upon  by  the  force  of 
the  discharge,  it  would  move  in  the  straight  line  A  £, 
and  after  a  time,  t,  would  reach  the  point  P  ;  but  it  is 
constantly  drawn  to  the  earth  by  the  force  of  gravity, 
and  instead  of  being  found  at  the  point  P,  it  is  found 
at  the  point  m,  situated  at  a  distance  below  P  equal  to 
the  distance  which  it  would  fall  in  the  same  time  under 
the  influence  of  gravity,  or  \gt2,  g  being  the  velocity 
generated  by  gravity  in  a  second  of  time. 

The  distance  PC  is  equal  to  x  tan.  <£;    the  distance 

mCj  or  y,  is  equal  to  this  distance  diminished  to  ±gt2,  or, 

y=#tan.  <p-\gt2) 

x 
x=t  l^cos.  £,  or  t=-y •     Substituting  this  for  t  in 

the  preceding  equation,  it  becomes, 

g  x2 


y=x  tan  <f>- 


2       F2cos.20 


MOTION  IN    VACUO.  397 

From  the  laws   which  govern   falling  bodies,    F== 


V'lgH,  or  V2—^gH;  in  which  H  is  the  height  due 
to  the  velocity  V.      Substituting  this  value  of  V2,  the 

equation  becomes, 

x2 

y=x  tan.  $—-7-7? r*~i  (1) 

y  r     4:B  cos.2  </>'  v  J 

which  is  the  equation  of  a  parabola. 
From  the  same  figure  we  obtain — 

y=Vt  sin.  <t>-igt2.  (2) 

#=  Vt  cos.  </>.  (3) 

*=        ®     „.  (4) 

K  COS.  0  v    7 

2d.  To  determine  the  vertical  ascent  and  horizontal 
range  of  the  projectile,  differentiate  equation  (1),  and 

place  the  value  of  -^=0;  whence  we  obtain, 
dx 

X—  4  Hsin.<t>  cos.tf>=:  2  J7  sin.  20.  (5) 

^ X  being  the  abscissa  of  the  highest  point, 

Y"=^rsin>.  (6) 

The  first  value  of  X  shows,  that  the  range  can  he  ob- 
tained with  two  angles  of  projection,  provided  they  be 
complements  of  each  other  ;  the  second  value  shows,  that 
the  greatest  range  corresponds  to  an  angle  of  45°,  and 
that  this  range  is  equal  to  twice  the  height  due  to  the  ve- 
locity ;  and,  also,  that  variations  in  the  angle  of  fire 
produce  less  variations  in  range  as  the  angle  of  fire  ap- 
proaches 45°. 

3d.  If  two  projectiles  be  thrown  under  the  same  angle, 

with  different  initial  velocities,  V  and  V\  the  ranges 

being  X  and  X \  we  have, 

Y2  V'2 

X=2#sin.20= — sin.  20,  and  X'— sin.  20; 

9  9 


398        SCIENCE   OF   GUNNERY. MOTION   IN  VACUO. 

and  from  these  we  nave, 

V  _<^  (7) 

Therefore,  under  the  same  angle  of  fire,  the  ranges  are 
proportional  to  the  squares  of  the  velocities ;  and  recip- 
rocally, the  velocities  are  proportional  to  the  square  roots 

of  the  ranges. 

ds 
4th.    The  velocity  at    any  point  is  equal  to  -j,  or 

du2-\-dx2 
v*=-^—j-2 — .    Substituting  the  values  of  dy  and  dx, 

obtained  by  differentiating  equations  (2)  and  (3),  we 

have 

v*=  V2-2  Vgtsm.<t>+gH2. 

Substitute  for -2  Vgt&m.<P+gH2  its  value -2gy,  de- 
rived from  equation  (2),  we  have, 

v2=  V2-2gy. 
Keplace  V2  by  2gH,  and  reducing,  the  expression  be- 
comes, 

v=V2g(H-y).  (8) 

This  shows  that  the  velocity  of  a  projectile,  at  any 
point,  depends  on  its  height  above  the  muzzle  of  the  piece  / 
and  that  it  is  equal  to  that  which  is  attained  in  falling 
through  the  height  (H—y).  It  also  shows  that  the  ve- 
locity is  least  when  y  is  greatest,  or  at  the  summit  of  the 
trajectory ;  and  that  the  velocities  at  the  two  points  in 
which  the  trajectory  cuts  the  horizontal  plane  are  equal. 

5th.  The  total  time  of  flight  may  be  determined  by 
substituting  the  value  of  X—  4i^sin.4>cos.<£,  equation 
(5),  in  equation  (4),  which  becomes 

4j£Tsin.</)_  Fsin.^  (9) 


MOTION    IN    VACUO.  399 


If  </>=45°,  sm.cp=V%1  and  V=VgX.     Calling  T  the 
time  of  flight,  we  have, 


'      V    \q      V   16.07     T 


Hence  the  time  of  flight  for  an  angle  of  45°  is  equal 
to  the  square  root  of  the  quotient  of  the  range  divided  by 
one-half  of  the  force  of  gravity ;  or,  it  is  approximately 
equal  to  one-fourth  of  the  square  root  of  the  range  ex- 
pressed in  feet 

6th.  The  tangent  of  the  angle  made  by  a  tangent 

line  at  any  point  of  the  trajectory  is  equal  to  -X  which 

is  obtained  by  differentiating  equation  (1) ;  calling  this 

angle  0,  we  have, 

x 

tan.(9=tan.w> == .  (10) 

r     2^cos.2tf>  v    J 

Substitute  the  value  of  JT=4  H  sin.^  cos.0,  the  angle 
of  fall  on  horizontal  ground  is  tan.0=  —  tan.0 ;  that  is  to 
say,  the  angle  of  fall  is  equal  to  the  angle  of  projection, 
measured  in  an  opposite  direction. 

7th.  The  position  of  a  point  being  given,  to  find  the 
initial  velocity  necessary  to  attain  it,  let  a  and  b  be  the 
horizontal  and  vertical  co-ordinates  of  this  point  of  the 
curve,  and  e  its  angle  of  elevation.  Substituting  these 
quantities  in  equation  (1),  and  recollecting  that  tan. 

e=  -,  we  have, 
a 

a  COS.e 

H- 


4  sin.  (<£  —  e)-  cos.0' 

or,  7=4  /■     ,  a9  c°^.  (11) 

V    2  sin.(<2>— eVcos.o!) 


400  SCIENCE    OF    GUNNERY. INITIAL    VELOCITY. 

8th.  The  position  of  a  point  being  given,  to  find  the 
angle  of  fire  necessary  to  attain  it.  Substituting  a  and 
b  for  x  and  y  in  equation  (1),  we  have, 

~  9 

b=a  tan.^. 


4i7cos.20 
from  which  to  determine  </>. 

Making  tan.<£=a,  we  have,  cos.2<£= ;  which  be- 
ing substituted  in  the  above  equation  gives— 

a=tan.0=:-(2^r=Li/4S'T^4^3^y        (12) 

The  two  values  of  tan.^  show  that  the  point  may  be 
attained  by  two  angles  of  projection;  and  the  radical 
shows  the  solution  of  the  problem  is  possible  when  the 
quantity  under  it  is  positive  /  or, 

4:H2>4:JIb+a\ 

412.  Practical  application  of  formula.  The  preced- 
ing formula  will  only  be  found  to  answer  in  practice  for 
projectiles  which  experience  slight  resistance  from  the 
air,  or  for  heavy  projectiles  moving  with  low  velocities, 
as  is  commonly  the  case  with  those  of  mortars  and 
howitzers. 

The  following  table  gives  the  difference  between  the 
observed  and  calculated  times  of  flight  of  the  French  8 
and  10-inch  mortar  shells,  weighing  64  and  119  lbs. 
respectively.  The  initial  velocities  being  unknown,  the 
times  are  calculated  from  the  observed  ranges. 

The  observed  times  are  invariably  greater  than  the 
calculated  times,  as  might  be  expected  from  the  resist- 
ance of  the  air,  which  retards  the  motion  of  projectiles. 


PRACTICAL    APPLICATION    OF    FORMULA. 


401 


Kind  of 
projectiles. 

■fi.'S 

"S3  o 

Ranges  at  angles  of 

Times  of  flight. 

4 

5° 

30° 

45° 

30° 

Observed. 

Calcu- 
lated. 

Observed. 

Calcu- 
lated. 

Kilog. 

0.234 

Meters. 

343 

Meters. 

290 

Seconds. 

9.8 

Seconds. 

8.4 

Seconds. 

6.8 

Seconds. 

5.8 

8-inch. 

0.351 
0.585 

629 
1146 

561 
1011 

12.9 
16.0 

11.3 
15.3 

10.0 
12.3 

8.1 
10.9 

0.994 

1792 

1690 

20.8 

19.2 

16.9 

14.1 

0.468 

457 

383 

11.0 

9.7 

7.5 

6.8 

0.693 

734 

637 

14.0 

12.2 

10.0 

8.7 

10-inch. 

1.054 

1132 

980 

17.0 

15.2 

12.0 

10.2 

1.405 

1555 

1355 

20.0 

17.8 

14.0 

12.6 

1.639 

1757 

1516 

23.0 

18.9 

15.0 

13.4 

The  next  table  shows  the  observed  and  calculated 
ranges,  for  30°  elevation,  and  the  observed  ranges  for 
45°  elevation,  for  the  above  projectiles,  the  initial  veloc- 
ities being  the  same  for  each  projectile. 


Kanges 

of  10-inch  Mortar  Shells. 

Ranges  of  8-inch  Mortar  Shells. 

45° 

30° 

45° 

30° 

elevation. 

elevation. 

elevation. 

elevation. 

Calcu- 

Calcu- 

Observed. 

Observed. 

lated. 

Difference 

Observed. 

Observed. 

lated. 

Difference 

Meters. 

Meters. 

Meters. 

Meters. 

Meters. 

Meters. 

Meters. 

Meters. 

457 

383 

396 

+  13 

343 

290 

298 

+    8 

734 

637 

637 

0 

629 

561 

545 

—16 

1132 

980 

982 

+    2 

1146 

1011 

993 

—13 

1555 

1355 

1350 

—  5   i 

1792 

1690 

1552 

—138 

1757 

1516 

1522  ■ 

+    6 

It  appears  from  the  foregoing  tables,  that  the  ranges 
of  mortars  with  different  degrees  of  elevation,  can  be 
calculated  up  to  about  1,400  yards  from  equation  (5), 


or, 


26 


X=2^rsin.  20, 


402    SCIENCE  OF  GUNNERY. RESISTANCE  OF  THE  AIR. 

and  the  times  from  equation  (4),  or 

X 


T= 


T^COS.   <j> 


RESISTANCE  OF  THE  AIR. 

413.  Importance  of  considering  it.  A  body  moving 
in  the  air  experiences  a  resistance  which  diminishes  the 
velocity  with  which  it  is  animated.  That  the  retarding 
effect  of  the  air,  on  projectiles  moving  with  high  veloc- 
ities, is  very  great,  is  seen  by  comparing  the  actual 
ranges  of  projectiles  with  those  computed  under  the 
supposition  that  they  move  in  vacuo.  Thus,  it  has  been 
shown  that  certain  cannon-balls  do  not  range  one-eighth 
as  far  in  the  air  as  they  would  if  they  did  not  meet 
with  this  resistance  to  their  motion;  and  small-arm 
projectiles,  which  have  but  little  mass,  are  still  more 
affected  by  it. 

414.  Law  of  resi§tance.  Incompressible  fluid.  The 
resistance  experienced  by  a  plane  surface  moving  parallel 
to  itself  through  an  incompressible  fluid,  is  equal  to  the 
pressure  of  a  column  of  the  fluid,  the  base  of  which  is 
the  moving  surface,  and  its  height  that  due  to  the  ve- 
locity with  which  the   surface  is  moved  through  the 

fluid,  or,  from  the  law  of  falling  bodies,  h= •   in 

y 
which  h  is  the  height,  v  the  velocity,  and  g  the  force  of 

gravity. 

The  resistance  on  a  given  area  is  therefore  propor- 
tional to  the  square  of  the  velocity,  and  the  density  of 
the  fluid  medium. 

Let  d,  «9J  and  v  represent  the  density  or  weight  of  a 


LAW    OF    EESISTANCE.  403 

unit  of  volume  of  the  fluid,  the  area  pressed  upon,  and 
the  velocity  of  the  moving  surface,  respectively,  and  p  the 
resistance  in  terms  of  the  unit  of  weight,  and  we  have, 

9=MS^  (13) 

in  which  h  is  a  coefficient  to  be  determined  by  experi- 
ment. 

Compressible  fluid.  If  the  medium  be  formed  of  com- 
pressible gases,  as  the  atmosphere,  the  density  in  front 
of  the  moving  body  will  be  greater  than  that  behind  it ; 
and  it  will  be  readily  seen  that  the  body  will  meet  with 
a  resistance  which  increases  more  rapidly  than  the  square 
of  the  velocity,  in  such  a  manner  that  the  coefficient  \ 
or  the  density  of  the  medium,  d,  should  be  increased  by 
a  quantity  which  is  a  function  of  the  velocity  itself,  or, 
what  is  the  same  thing,  by  adding  another  term  to  the 
resistance  which  shall  be  proportional  to  the  cube  of  the 
velocity. 

In  examining  the  table  of  resistances,  obtained  by 
Hutton  from  firing  a  one-pound  ball  into  a  ballistic  pen- 
dulum, at  different  distances,  and  with  velocities  vary- 
ing from  300  to  1,900  feet,  Piobert  found,  that  if  v2  in 
the  foregoing  expression  be  replaced  by  the  binomial 

term,  (  v2-\ —  i,  m  which  -—_ ,  the    expression 

would  nearly  satisfy  the  results  of  experiments. 

hd 
Calling  A= — ,  and  ttR*  the  area  of  the  cross  section 

of  a  projectile,  the  general  expression  for  the  resistance 
in  air  becomes, 

9=AnB>(l+f)v\  (14) 


\ 

404    SCIENCE  OF  GUNNERY. RESISTANCE  OF  THE  AIR. 

In  this  expression,  A  is  the  resistance,  in  pounds,  on 
a  square  foot  of  the  cross-section  of  a  projectile  moving 
with  a  velocity  of  one  foot;  r  is  a  linear  quantity  de- 
pending on  the  velocity  of  the  projectile.  For  all  service 
spherical  projectiles,  ^4. =.000514;  and  for  all  service 
velocities  7*=  1427  feet.  The  value  of  A  for  the  oblong 
projectiles  of  our  service  remains  to  be  determined  by 
experiment;  it  is  stated  in  the  French  Aide-Memoire 
that  for  a  certain  oblong  bullet  (presumed  to  be  that  of 
the  carabine  a  tige)  ^.=.000342,  or  that  the  resistance 
of  the  air  is  one-third  less  on  the  pointed  than  on  the 
spherical  form. 

The  coefficient  A,  being  a  function  of  the  density  of 
the  air,  its  value  depends  on  the  temperature,  pressure, 
and  hygrometric  condition ;  in  the  above  value  the 
weight  of  a  cubic  foot  of  air  =.075  lb.,  at  a  temperature 
of  60°  Fahr.,  and  for  a  barometrical  pressure  of  29.5 
inches. 

If  the  surface  of  the  projectile  be  rough  or  irregular, 
the  value  of  this  coefficient  will  be  slightly  too  small. 

Example. — What  is  the  pressure  of  the  air  on  a  42-pdr.  shot 
moving  with  a  velocity  of  1,500  feet? 

— 2     ,/       1500\ 

p=.000514  X  3.1415  x  .29  X  15002(  1  +  — -  I  =629.3  lbs 


/       150o\ 
(1  +  l427j 


415.  Fall  of  a  projectile  In  the  air.  The  motion  of 
a  body  falling  through  the  air,  will  be  accelerated  by 
its  weight,  and  retarded  by  the  buoyant  effort  of  the 
air,  and  the  resistance  which  the  air  offers  to  motion. 
As  the  resistance  of  the  air  increases  more  rapidly  than 
the  velocity,  it  follows  that  there  is  a  point  where  the 
retarding  and  accelerating  forces  will  be  equal,  and  that 
beyond. this,  the  body  will  move  with  a  uniform  veloc- 


FALL    OF   A    PROJECTILE   IN    THE    AIR.  405 

ity,  equal  to  that  which  it  had  acquired  down  to  this 
point. 

The  buoyant  effort  of  the   air  is  equal  to  the  weight 

of  the  volume   displaced,  or  P—  ;  in    which  P  is  the 

weight  and  D  the  density  of  the  projectile,  and  d  the 
density  of  the  air. 

When  the  projectile  meets  with  a  resistance  equal  to 
its  weight,  we  shall  have, 

P(l-§)=^v(l+^);  (15) 

in  which  the  weight  of  the  displaced  air  is  transferred 
to  the  first  member  of  the  equation.  As  the  density 
of  the  air  is  very  slight   compared  to  that  of  lead  or 

iron,  the   materials  of  which  projectiles  are  made,    ~> 

may  be  neglected.     Making  this  change,  and  substitu- 

4 
ting  for  P,  —nil3 1)  (g  having  been  divided  out  of  the 

o 

second  member,  should  be  omitted  in  the  first),  the  ex- 
pression for  the  final  velocity  reduces  to 

The  resistance  on  the  entire  projectile  for  a  velocity 

P 

of  1  foot,  is  AttR2  ;  dividing  this  by  — ,  or  the  mass,  we 

if 

get  the  resistance  on  a  unit  of  mass. 

Calling  this  — ,  we  have, 

zc 

1      AnB?       a  P 

9 


406 


SCIENCE  OF  GUNNERY. LOSS  OF  VELOCITY. 


Substituting  for  P  its  value  in  the  equation  of  verti- 
cal descent,  we  have, 


2^=*2(i+^); 


from  which  we  see  that  v  depends  only  on  c  /  but 

2  ED 


€= 


3   gA 


(17) 


hence,  the  final  velocity  of  a  projectile  falling  through 
the  air  is  directly  proportional  to  the  product  of  the 
diameter  and  density  of  the  projectile,  and  inversely 
proportional  to  the  density  of  the  air,  which  is  a  factor 
of  A. 


SHOT. 

SHELLS. 

MUSKET 
BULLET. 

Calibre 

42 

24 

18 

12 

6 

13  in 

10  in 

8  in. 

24 
pdr. 

Round, 
69  diam. 

Final  velocity  of  de- 
scent in  air,  in  feet 
per  second 

485 

455 

425 

410 

360 

585 

505 

445 

375 

213 

Value  of  c 

4899 

4247 

3650 

3370 

2518 

6436 

4677 

3570 

2754 

804 

The  value  (<?)  may  be  said  to  represent  the  relative 
ability  of  a  projectile  to  overcome  the  resistance  of  the 
air. 


LOSS  OF  VELOCITY  BY  EESISTANCE  OF 
THE  AIR 

416.  Equation§  of  motion.  For  the  purpose  of  de- 
termining the  velocity  which  a  projectile  loses  by  the 
resistance  of  the  air,  in  moving  through  a  certain  dis- 
tance, 00j  the  force  of  gravity  may  be  disregarded ;  in 
which  case  the  trajectory  described  will  be  a  right  line. 


LOSS    OF    VELOCITY    BY   THE    AIR.  407 

Let  V  be  the  initial  velocity,  and  v  the  remaining  ve- 
locity at  the  end  of  the  distance  a?. 

The  expression  for  the  resistance  of  the  air  is,  as  we 
have  seen, 

But  we  know  that  the  retarding  force  of  the  air  is  equal 
to  the  mass  of  the  projectile  against  which  it  acts,  multi- 
plied by  the  first  differential  coefficient  of  the  velocity, 
regarded  as  a  function  of  the  time,  with  its  sign  changed, 

and  that  —  is  the  mass  of  the  projectile.  We  have, 
therefore, 

Eecollecting  that  jP=-7riJ3Z>,  and  that  2c= -p,  the 

equation  reduces  to, 

dv_      v2/       v\ 

Integrating  this  equation  between  the  limits  0  and  %, 
which  correspond  to  V  and  v,  we  have, 

T 

+  V 
To  obtain  a  relation  between  the  space  and  velocity. 

we  have  v—-j-i  ovdt— — ;  substituting  this  in  the  equa- 
tion for  the  intensity  of  the  retarding  force,  and  reduc- 
ing, we  have, 

dv 


A       1\      2c,  '  v. 

\v-v)-Tl°^--r  (18) 


dx=:  —  2c 

V 


H) 


408  SCIENCE  OF  GUNNERY.— LOSS  OF  VELOCITY. 

Integrating  between  the  same  limits  as  in  the  preced- 
ing case,  we  have, 


r  x 

1  + 

2c 


x=2clog. -or   l+£sjflHrjfV 


(19) 


T 

1+V 


Solving  this  equation  with  reference  to  v,  we  have, 

r 

v= 


('+T>*- 


(20) 


Substituting,  in  equation  (18),  x  for  its  value  given 
in  equation  (19),  we  have, 

t=2c  (l*\-X.  (21) 

The  logarithms  in  the  above  equations  belong  to  the 
Napierian  system,  and  are  obtained  by  multiplying  the 
corresponding  common  logarithm  by  2.3026:0=2.713. 

Practical  remarks.  Equation  (19)  gives  the  space 
passed  over  by  a  certain  projectile  when  the  velocities 
at  the  commencement  and  end  of  the  flight,  are  known. 

Equation  (20)  gives  the  remaining  velocity  when  the 
initial  velocity  and  the  space  passed  over  are  known. 

Equation  (21)  gives  the  time  of  flight  when  the  ve- 
locities at  the  beginning  and  end  and  the  space  passed 
over,  are  known. 

The  distance  at  which  the  velocity  Fls  reduced  to  t\ 
and  the  duration  of  the  trajectory,  being  proportional  to 
c,  are  directly  proportional  to  the  product  of  the  diame- 
ter and  density  of  the  projectile,  and  inversely  propor- 
tional to  the  density  of  the  air.  This  fact  shows  the 
great  advantage,  in  point  of  range,  to  be  derived  from 


THEORY.  409 

using  large  projectiles  over  small  ones,  of  solid  projec- 
tiles over  hollow  ones,  of  leaden  projectiles  over  iron 
ones,  and  of  oblong  projectiles  over  round  ones. 


FORM  OF  PROJECTILE. 

417.  Theory.  When  a  body  moves  through  the  air, 
the  gaseous  particles  in  front  are  crowded  upon  each 
other  until  they  meet  with  a  certain  resistance,  after 
which  they  move  off  laterally,  and  finally  pass  around 
and  arrange  themselves  in  rear  of  the  moving  body. 
It  is  evident  that  the  difference  of  the  densities,  or 
pressures,  front  and  rear,  depends  on  the  velocity  with 
which  the  displaced  particles  rearrange  themselves  after 
displacement ;  and  this,  in  turn,  depends  on  the  shape, 
and  extent  of  the  surfaces  of  the  moving  body.  The 
best  form  for  a  projectile  can  only  be  determined  by  ex- 
periment, as  theory  and  experiment  do  not  agree  in 
their  results. 

According  to  theory,  if  a  plane  of  given  area  be 
moved  through  the  air,  it  meets  with  a  resistance 
which  is  proportional  to  the  square  of  the  sine  of  the 
ans4e  which  its  direction  makes  with  that  of  motion. 

The  experiments  of  Hutton  with  low  velocities  show 
that  this  is  only  true  in  cases  of  0°  and  90° ;  that  from 
90°  up  to  50°  or  60°,  the  resistance  is  nearly  propor- 
tional to  the  sine ;  beyond  this,  it  decreases  a  little  more 
rapidly  than  the  sine,  but  not  so  rapidly  as  the  square 
of  the  sine : 


410 


SCIENCE    OF    GUNNERY. LOSS    OF    VELOCITY. 


For  an  angle  of  22°  it  is  only  \  the  resistance  proportional  to  the  sine. 

a  U      14.0  a  \_  u  ►<  u 

3 

«  «  Qio         "1  "  **  M 

tt  U  40  «  1  M  «  U 

*  5 

«  U  0°  <<  1  «  "  U 


418.  Experiments  of  Hutton  and  Borda.  The  fol- 
lowing are  the  results  of  the  experiments  made  by 
Hutton  and  Borda,  on  the  resistances  experienced  by 
different  forms  of  solids  moving  through  the  air  with 
velocities  varying  from  3  to  25  feet  per  second. 


HUTTON1  S    EXPERIMENTS.       VELOCITY,    10    FEET. 

Kind  of  surface. 

Experimental 
resistance. 

Theoretical 
resistance. 

| 

No.  1  Hemisphere  (convex 

surface  in  front), 
No.  2  Sphere, 

No.    3   Cone,   elements   in- 
clined to  the  axis  25°  42', 
No.  4  Disk, 

No.   5   Hemisphere    (plane 

surface  in  front), 
No.  6  Cone  (base  in  front), 

119 

124 

126 

285 

288 
291 

144 
144 

53 

288 

288 
288 

Fig.  136. 

BORDA. 

Kind  of  surface. 

Experimental 
resistance. 

Theoretical 
resistance. 

| 

No.  1,  Prism,  with  triangular 

base, 
No.  2,      "                     M 

No.  3,      "         semi-ellipse, 

No.  4,      "          ogee, 

100 
52 

43 

39 

100 
25 

50 

41 

Fig.  137. 

CONCLUSIONS.  411 

419.  Conclusions  The  foregoing  experiments  show: 
1st.  That  the  results  of  theory  do  not  agree  with  those 
of  practice.  2d.  That  rounded  and  pointed  solids  suffer 
less  resistance  from  the  air  than  those  which  present 
flat  surfaces  of  the  same  transverse  area,  but,  at  the 
same  time,  the  sharpest  points  do  not  always  meet  with 
the  least  resistance.  3d.  That  where  the  front  surfaces 
were  the  same,  the  resistance  was  least  with  those  in 
which  the  posterior  surfaces  were  the  flattest.  4th. 
That  the  ogeeval  form,  or  the  form  of  the  present  rifle- 
musket  bullet,  experiences  less  resistance  than  any  other 
tried. 

These  experiments,  as  before  remarked,  were  made 
with  low  velocities,  compared  to  those  which  ordinarily 
actuate  projectiles,  and  the  conclusions  which  have  been 
drawn  from  them  may  not  be  strictly  applicable  in  prac- 
tice. Now  that  oblong  projectiles  are  used  in  all  kinds 
of  fire-arms,  it  is  important  to  determine  that  form  which 
will  be  least  affected  by  the  resistance  of  the  air.  It  is 
evident  that  that  form  will  be  the  best  which,  on  trial, 
is  found  to  give  the  least  value  to  A  in  equation  (14), 
or,  what  is  the  same  thing,  to  give  the  greatest  value  to 
c  in  equation  (21).* 


*  The  author  proposes  the  following  method  of  determining  the  value  of  c  by  the 
electro-ballistic  machine. 

Establish  four  targets  in  the  line  of  fire,  in  such  manner  that  the  first  shall  be 
near  the  piece,  the  second  shall  be  at  a  distance  x  from  the  first,  the  third  at  a 
distance  2x  from  the  first,  and  the  fourth  at  a  distance  of  4x  from  the  first ;  let  t,  t\ 
and  t"  represent  the  intervals  of  time  corresponding  to  the  distances  between  the 
targets,  respectively;  let  v  be  the  velocity  at  the  middle  point  between  the  first 
and  third  targets,  or  at  the  distance  x,  and  let  v'  be  the  velocity  at  the  middle  point 
between  the  first  and  fourth  targets,  or  at  the  distance  2x. 

Equation  (21)  becomes 

2c     2e    X    or  2^=2c_^_# 
v       V     r  V     v      r 


412       SCIENCE    OF    GUNNERY. TRAJECTORY    IN    AIR. 

TRAJECTORY  IN  AIR. 

420.  Bifflcuitie§  of  the  problem.  In  consequence  of 
the  variable  nature  of  the  resistance  of  the  air,  it  has 
been  found  impossible  to  integrate  the  differential  equa- 
tions of  the  real  trajectory,  even  under  the  supposition 
that  this  resistance  varies  in  as  simple  a  ratio  as  the 
square  of  the  velocity.  Several  distinguished  mathe- 
maticians have  obtained  expressions  which  approximate 
to  the  true  results,  but  the  expressions  are  generally  too 
complicated  to  be  of  much  practical  value. 

421.  Diction's  method.  Captain  Didion,  professor 
of  gunnery  in  the  artillery  school  at  Metz,  however, 
furnishes  an  approximate  solution  to  this  difficult  ques- 
tion, which  may  be  used  in  practice.  To  do  this,  he 
considers  the  resistance  of  the  air  equal  to 


Mffft+tyf; 


and  by  assuming  a  mean  value  for  the  different  inclina- 
tions of  the  elements  of  the  trajectory  to  their  horizon- 

ds 
tal  projections,  which  makes  -r-  constant,  he  is  able  to 


2  c 
Since  ■—  is  the  same  for  all  the  distances,  we  have 

t—t'—~ 
2c     fit  2c     2x      ,  r 

f— r 1,  or  c—  -jz -— 

v      r  v        r  2 


From  the  note  on  page  389,  we  are  at  liberty  to  place  v— =—  and  v'— ■— •  substitut- 

t  t 

ing  these  values  in  the  preceding  equation,  reducing  and  changing  the  signs  of  both 
numerator  and  denominator  of  the  second  member,  we  have 

2x1  f—t+~ 
c- 


t"—2t' 

"Which  equation  gives  the  value  of  c  in  terms  of  t,  t',  t",  and  which  can  be  deter- 
mined by  taking  the  mean  of  several  shots,  with  the  electro-ballistic  machine,  at 
the  different  distances,  x,  2x,  and  4x. 


413 

integrate  the  differential  equations,  and  place  them  un- 
der the  following  forms : 

ft         fl$ 

y=x  tan.  (j> —~  -« r  B  ; 

*  2   V2  cos.20      \ 

OS 

Tan.  d=  tan.0  —  a-™ tt.1; 

X  -r.  T^COS.  0     1 

t=  «r- JJ  ;  v=. yt- 

V  cos.  <$>      7  cos.  e      U 

The  same  notation  being  preserved  as  in  the  equa- 
tions in  vacuo  (page  397),  it  will  be  perceived  that  the 
equations  in  air  differ  from  those  in  vacuo,  by  the  mul- 
tipliers B,  I,  ./>,  and  U,  respectively. 

The  multiplier  B  relates  to  the  fall  of  the  projectile ; 
7,  to  the  inclination ;  Z>,  to  the  duration ;  and  U,  to  the 

velocity ;  they   are   each   functions  of  —  and  — -;   in 

which  a  is  the  constant  relation  of  the  arc  to  its  projec- 
tion, V,=  7^  cos.  0,  and  c  and  r  are  co-efficients  of  the 
formula  for  the  resistance  of  the  air.  (See  pages  403 
and  406.)  The  general  expression  for  a  particular  mul- 
tiplier, B  for  instance,  is  B( — ;  - — -  V 

The  values  B,  I,  D,  and  TJ%  for  such  values  of  c  and 
r  as  are  likely  to  arise  in  service,  have  been  computed, 
and  arranged  in  tabular  form ;  these  tables,  their  con- 
struction, and  use,  are  explained   in  chapter  XIII. 

So  long  as  the  inclination  of  the  trajectory  is  slight,  « 
differs  but  slightly  from  unity;  for  an  angle  of  15°  it 
does  not  exceed  0.01 ;  and  as  it  only  enters  into  the 
term  which  relates  to  the  resistance  of  the  air,  the  error 


414       SCIENCE    OF    GUNNERY. TRAJECTORY   IN    AIR. 

does  not  exceed  a  pressure  corresponding  to  0.25  in.  in 
the  height  of  the  barometer ;  it  may,  therefore,  be  re- 

garded  as  unity,  and  — -  reduces  to  -.     The  same  with 

G  G 

regard,  to  — — •   or —  ;  as  a  cos.  tj>,  when  0=10°, 

differs  only  about  0.01  from  unity  ;  and  this  expression 

y 

may  be  reduced  to  — .     When  the  angle  of  projection 

does  not  exceed  3°,  cos.  <p  differs  only  .001  from  unity, 
and  we  can  everywhere  replace  V  cos.  0  by  V.     Under 

COS   0 

this  angle,  — —   differs  but  slightly  from  unity,  and  we 

V 
have   v=  — f  which  is  the  same  as  if  motion  took  place 

in  a  horizontal  plane. 

All  cases  of  the  movement  of  projectiles  which  occur 
in  practice,  may  be  divided  into  three  distinct  classes : 
1st,  When  the  angle  of  projection  is  slight,  or  does  not 
exceed  3°,  as  in  the  ordinary  fire  of  guns,  howitzers,  and 
small-arms ;  2d,  When  the  angle  of  projection  is  greater 
than  this,  but  does  not  exceed  10°  or  15°,  as  in  ricochet 
fire,  &c. ;  3d,  When  the  angle  of  projection  exceeds  15°, 
as  in  the  fire  of  mortars. 

422.  l§t  class.  For  small  angles  of  projection,  as  in 
guns,  howitzers,  and  small-arms. 

For  slight  variations  of  the  angle  of  projection  above 
or  below  the  horizon,  the  form  of  the  trajectory  may  be 
considered  constant ;  and  when  the  object  is  but  slightly 
raised  above,  or  depressed  below  the  horizontal  plane, 
it  may  be  considered  as  in  this  plane. 

In  consequence  of  the  windage,  and  the  balloting  of 


FIEST    CLASS.  415 

the  projectile  which  results  from  it,  the  projectile  does 
not  always  leave  the  bore  in  the  direction  of  the  axis. 
The  angle  formed  by  the  line  of  departure  and  the  axis 
of  the  piece,  is  called  the  angle  of  departure.  For  guns 
in  good  condition,  the  vertical  deviations  do  not  exceed 
5',  and  for  howitzers  10';  the  side  deviations  never  ex- 
ceed 4'  30".  To  obtain  exact  results,  therefore,  it  is 
necessary  to  correct  the  angle  of  projection  for  the  angle 
of  departure,  when  the  latter  is  known. 

T-     1  T  ....  -,    COS.0 

Under  the  supposition  that  a,  cos.  </>,  and are 

each  equal  to  unity,  the  equations  of  the  trajectory  in 
air  may  be  reduced  to — 

r=»***-fii*;  (22) 

Tan.0=tan.0-gr  *  /;  (23) 

teyD;  (24) 

v=^.  (25) 

Knowing  the  weight  and  diameter  of  the  projectile,  c 

can  be  calculated   by  the  formula   c=~- —  if  it   be 

SgA 

not  found  in  the   table  which    accompanies   it.     We 

x  V 

know  -  and  — ,  and  by  means  of  the  tables  can  deter- 

c  r 

mine  the  desired  values  of  B,  I,  D,  and  TI. 

Of  the  three  things,  the  initial  velocity,  J7",  the  dis- 
tance of  the  object,  X,  and  the  angle  of  projection,  </>,  two 
being  known,  to  determine  the  third. 

1st.  To  determine  the  angle  of  projection,  <p. — Make 
y=0  in  equation  (22),  and  solve  it  with  reference  to 


416       SCIENCE    OF    GUNNERY. TRAJECTORY    IN    AIR. 

tan.  $  we  have, 

tan.  <b=l—B. 
2  V2 

JEJxample. — Find  the  angle  of  projection  necessary  to  throw  a 

12-pdr.  shot  1800  feet,  with  an  initial  velocity  of  1500  feet.     We 

x      1800  V      1500  „ 

have  F=1500  feet;  -  =  ——=0.5336; — =——  =  1.054.      From 
'  c       3370  '  r        1427 

32  17    1800 
Table   (l),  .#=1.449;   tan.  </>=-——.  ==  1.449.  =  0.01864.  <j>  = 

Z         loUO 

1°  05'. 

2d.  To  determine  the  initial  velocity,  V,  make  y=0, 
in  equation  (22),  solve  it  with  reference  to  V,  and  mul- 
tiply both  members  by  -,  we  have. 


)/~B~  t  V   2  tan.0~~2* 


X 

Having  the  values  of  —  and  q,  seek  in  table  (5)  for 

G 

X  V 

the  value  of  — ,  the  value  of  — ,  which  gives  that  of  q  ; 
c  r 

multiply —  by  1427  and  we  shall  have  V. 
r 

Example.— Find  the  initial  velocity  of  a  12-pounder  shot  which, 
fired  under  an  angle  of  1°  05',  has  a  range  of  1800  feet. 


1  / 16.08  x 

427  y        0.0181 


1800 

:0.8732. 


1427  V        0.01864 

—  =  1.05.      F=1.05  x  1427=1498.35  feet. 
r 

3d.  To  determine  the  range,  X. — Make  y=0  in  equa- 
tion (22),  obtain  the  value  of  X,  and  divide  both  mem- 
bers of  the  equation  by  g,  we  have, 

X-n      tan.*  V2 
—  Jj— —p. 

g  c\g 


FIRST    CLASS.  417 

Having  the  initial  velocity,  FJ  and  angle  of  projec- 
tion, 0,  we  can  determine,  —  and  p;  seek  in  table  (4), 

V  X 

for  the  value  of — ,  that  of — ,  which  gives  p;  having 
y  c 

X 

_,  multiply  it  by  <?,  and  we  have  X. 

c 

Example. — Find  the  range  of  a  12-pdr.  ball,  fired  under  an  angle  of 

1°  05',  with  an  initial  velocity  of  1500  feet. 

V 
c=3370;  _ _=1.0511;  tan.  </>= 0.0 1864. 
r 


0.01864      1500        rt„„.      ,£         .  . .       .,    X       KO,A    v      co.A 

Vx= . =  0.774;  (from  table    4), —  =  .5340; X—  .5340 

3370  16.08  v  !    c 

X  3370=1800  feet. 

The  slight  discrepancies  in  the  three  preceding  results,  arise  from 

the  neglected  decimals. 

In  firing  spherical  case-shot,  it  is  important  not  only 
to  know  the  time  of  flight,  in  order  to  regulate  the  fuze, 
but  it  is  important  to  know  that  the  projectile  will  have 
sufficient  remaining  velocity  to  render  the  impact  of  the 
contained  projectiles  effective. 

4th.  The  time  of  flight  can  be  obtained  from  equa- 

tion  (24),  or,  t=  -=jd).     Knowing  —  and  — ,  we  can  ob- 
tain the  corresponding  value  of  D  from  table  (3). 

Example. — Find  the  time  of  flight  of  a  12-pdr.  spherical  case-shot 
for  a  distance  of  1500  yards,  the  initial  velocity  being  1500  feet. 

*^f<»     1.335  J  Z=1^°  =  1.051  J  i>  =  1.859. 
c       3370  r      1427 

*=1^)1.859=5.58  seconds. 
1500 

5th.  The  remaining  velocity  can  be   obtained  from 

27 


418       SCIENCE    OF    GUNNERY. TRAJECTORY    IN   AIR. 

equation  (25),  or,  v—--.     Knowing  — and — ,  obtain 
±  \     /•>  jj  c  r 

from  table  (3)  the  corresponding  value  of   U. 

Example — Find  the  remaining  velocity  of  a  12-pdr.  spherical  case- 
shot  at  the  distance  of  1500  yards,  the  initial  velocity  being  1500  feet. 

*,!!??_l.a27;  .t^J.051;  ^=2.882;    ,-**»  =520  feet. 
c      3370  r  '  2.882 

This  velocity  is  more  than  sufficient  for  a  musket-bullet  to  disable  an 

animate  object  at  the  distance  of  1500  yds. 

423.  2<i  cia§s.  For  angles  of  projection  not  exceed- 
ing 10°  or  15°,  as  in  the  ricochet  fire  of  guns,  howitzers, 
and  mortars. 

The  formulas  are : 


g        x 


y=fl?tan.*-|T^?-A  (26) 


X 

tan^tan^-^W-Z  (27> 

*=*,*      A  (28) 

V  cos.0  v     7 

•=-5=£  (29) 

(Tcos.0 

If  the  object  be  on  a  level  with  the  piece,  the  solu- 
tion of  this  class  of  problems  is  the  same  as  those  of 
class  1st,  when  the  angle  is  very  small ;  if  not,  it  will 
be  necessary  to  substitute  for  V,  V/  =  F^cos.  </>,  and  after 
having  obtained  Vn  divide  it  by  the  cos.  0,  which 
gives  V. 

The  object  being  situated  at  the  distance  a  from  the 
piece,  and  at  the  distance  b  above  the  horizontal  plane 
passing  through  the  centre  of  the  muzzle,  is  seen  under 

an  angle  of  elevation  e,  for  which  tan.e=-.     One  of  the 


SECOND    CLASS.  419 

two  things,  the  initial  velocity  or  angle  of  projection 
being  known,  to  determine  the  other. 

1st.  To  determine  the  initial  velocity,  V.     Substitute 
in  equation  (26)  the  co-ordinates  a  and  b,  and  Vn'  solve 

it  with  reference  to  VJ /  substitute  tan.  e  for  -,   and    di- 

a 

vide  both  members  by  r,  we  have, 
V     1      /      f* 


VB       ry  tan.(/>  —  tan.e      q' 
Having  the  value  of  q,  seek  in  table  (5)  for  the  known 

value  of  -,  the  value  of  — i  corresponding  to  it,  and  mul- 
tiplying by ,  we  shall  have  V. 

COS.0 

Example. — Find  the  initial  velocity  of  an  8-inch  siege-howitzer  shell, 
which,  being  fired  under  an  angle  of  12°,  will  strike  an  object  situated 
1,000  feet  from,  and  20  feet  above,  the  muzzle  of  the  piece. 

20 
Tan.0=O.2125;  tan.e=  — —=0.0200;  tan.</>— tan.e=0.1925  ; 

coa.0-0.9781;  i_"™     0.2801;  f-JL  ,  /™Z?JW^ 
c        3570  *     1427  Y        0.1925 

V                      _      0.2150.  1427      „no  .    . 
0.2023;  —^  =  0.2150;    V==  — -— — =313  feet. 

2d.  To  determine  the  angle  of  projection.  The  result 
will  be  sufficiently  near  the  truth,  if  we  substitute,  in 
equation  (26),  Ffor  Vn  or  V cos.  0 ;  and  solving  it  with 
reference  to  tan.  0,  we  have, 

tan.0=tan.  e+  *L=  B, 

in  which  we  substitute  for  B  its  value,  corresponding 
to  _  and  — ,  obtained  from  table  (1). 


420        SCIENCE    OF    GUNNERY. TRAJECTORY   IN    AIR. 

Example. — What  angle  of  projection  is  necessary  for  an  8-inch 
siege-howitzer  shell  to  strike  an  object  situated  1000  feet  from,  and 
20  feet  above,  the  muzzle  ?     The  initial  velocity  being  313  feet, 

a      1000  V      313  20 

F=313  feet;  -=-—=0.2801;    -=-——  =  0.2193;  tan.e=  — — 
'  c      3570  '    r       1427  1000 

16.08.1000 

=  0.0200;  tan.  0=0.0200+ —-= 1,142  =  0.2084;    0=11°  28  . 

3132 

424.  3d  cia§§.  Properties  of  trajectories  under  high 
angles  of  projection. 

As  a  projectile  rises  in  the  ascending  branch  of  its 
trajectory,  its  velocity  is  diminished  by  the  retarding 
effect  of  the  air  and  the  force  of  gravity :  in  consequence 
of  the  resistance  of  the  air  alone,  the  velocity  continues 
to  diminish  to  a  point  a  little  beyond  the  summit  of 
the  trajectory,  where  it  is  a  minimum ;  and  from  this 
point  it  increases,  as  it  descends,  under  the  influence  of 
the  force  of  gravity,  until  it  becomes  uniform,  which 
event  depends  on  the  diameter  and  weight  of  the  pro- 
jectile and  the  density  of  the  air,  or,  in  other  words, 
upon  the  value  of  c. 

The  inclination  of  the  trajectory  decreases  from  the 
origin  to  the  summit,  where  it  is  nothing ;  it  increases 
in  the  descending  branch  from  the  summit  to  its  ter- 
mination, and  if  the  ground  did  not  interpose  an  ob- 
stacle, it  would  become  vertical  at  an  infinite  distance. 
An  element  of  the  trajectory  in  the  descending  branch 
has  a  greater  inclination  than  the  corresponding  element 
of  the  ascending  branch. 

Strictly  speaking,  the  trajectory  in  air  is  an  expoten- 
tial  curve  with  two  asymptotes;  the  first  is  the  axis  of 
the  piece,  which  is  tangent  to  the  trajectory  when  the 
initial  velocity  is  infinite ;  the  second  is  the  vertical  line 
toward  which  the  trajectory  approaches  as  the  horizon- 


THIED    CLASS. 


421 


tal  component  of  the  velocity  diminishes,  and  the  effect 
of  the  force  of  gravity  increases. 

The  curvature  of  the  trajectory  increases  in  the  as- 
cending branch,  to  a  point  a  little  beyond  the  summit. 
The  point  of  greatest  curvature  is  situated  nearer  the 
summit  than  the  point  of  minimum  velocity. 

In  the  fire  of  mortar  shells  under  great  angles  of  pro- 
jection, and  at  customary  distances,  the  trajectory  may 
be  considered  as  an  arc,  in  which  the  angle  of  fall  is 
slightly  greater  than  the  angle  of  projection.  In  the 
ascending  branch,  the  arc  commences  under  an  angle  of 
0,  and  terminates  under  an  angle  of  0 ;  the  ratio  of  the 
length  of  this  arc  to  its  projection,  or  a,  is  calculated 
for  all  arcs  from  5°  to  75°,  and  arranged,  in  groups  of 
fives  in  the  accompanying  table. 

The  value  of  a  is  considered  the  same  in  the  descend- 
ing as  in  the  ascending  branch. 


ARCS. 

a 

ARCS. 

a 

ARCS. 

a 

5° 

1.00127 

30° 

1.05306 

55° 

1.27583 

10 

1.00516 

35 

1.07596 

60 

1.38017 

15 

1.01184 

40 

1.10730 

65 

1.53433 

20 

1.02*165 

45 

1.14777 

70 

1.77772 

25 

1.03514 

50 

1.20189 

75 

2.20349 

The  multipliers,  B,  I,  D,  and  the  divisor,  U,  are  cal- 
culated for  the  values  —  and -.    and   they   are  em- 

c  r  '  J 

ployed  in   equations  (26),    (27),   (28),  (29),  as  in  the 
preceding  class  of  cases. 

1st.  Find  the  initial  velocity  of  a  mortar  shell,  know- 
ing the  range  and  angle  of  projection. 

We  know  — ,  and  by  solving  equation  (26)  as  before, 
c 


422       SCIENCE    OF    GUNNERY. TRAJECTORY    IN    AIR. 

we  have. 


r       r  V    tan.<£     * 


Having   determined  the  value  of  q,  seek   in  table 
(5)  the  value  of  — 'corresponding  to  it  for  — ;  then 

V  C 

multiply  it  by ,  and  we  have  V. 

r  J  J   a  COS.07 

Example. — What  initial  velocity  is  necessary  to  project  a  10-inch 
shell  1,800  feet,  under  an  angle  of  45°? 

For   a    10-inch    shell,    cr=r4677;    for  45°,    a  =  1.148;      — = 

c 


1.148.1800  1.148 


=  0.4418;    q 


4677  '    *        1427 


/ 16.08.  1800    „10^      .,     A 
\  /      ,  nnnn      —0.1369.      By  th( 

y      l.oooo  : 


aV 
aid    of  table    (5)   we  find   ^^0.1490 ;    and    from    this    we    get 

Tr      0.1490.1427        nn    m    A 
v=  ,  ,  ,»    „*«»,  =262  feet. 
1.148.0.7071 

2d.  To  determine  the  angle  and  velocity  of  fall,  and 
the  time  of  flight,  knowing  the  initial  velocity  and  range. 
Let  the  projectile  be  the  same  as  in  the  preceding  case. 

Example. — We  have  — =0.4418  ;  and  ^  =  0.1490  ;  from  ta- 
ble (1)  we  have  /=  1.291  ;  from  table  (2),  D  =  1.121 ;  and  £7=1.272. 
Substituting  the  proper  values  in  equation  (25)  we  have 

oo  1  *1      1  800 

Tan.  0=  1.0000- 262<a707i)2. 1.280= —1.159;  6=  —  49°  12'. 

The  negative  sign  indicates  that  the  angle  of  fall  is  measured  in  an 
opposite  direction  from  the  angle  of  projection.  Making  the  proper 
substitutions  in  equations  (28)  and  (29),  we  have 

1800     .1.127=10.95".  v=m^==    222   feet 


262.0.7071  1.272.0.6534 

3d.  To  determine  the  range,  knowing  the  initial  ve- 
locity and  angle  of  projection. 


TRAJECTORY    OF    OBLONG    PROJECTILE.  423 


• 


aV 

We  have  a,  and  — -';  make  y=o  in  equation  (26)  ; 
solve  it  with  reference  to  X,  and  multiply  both  mem- 
bers  by  — - ,  and  we  have, 

aX  jy      a  V     .       n 

—  B— sm.  2w>=/?. 

c  gc 

X  V 

Having  found  the  value  of  c  - ,  which  for  -    -  gives 

c  i 

p   (table  4)  ;  multiply  it  by—,  and  we  have  X. 

Example. — Find  the  range  of  a  10-inch  mortar  shell,  the  angle  of 
projection   of  which  is  45°,  and  the  initial  velocity  is  262  feet. 

aV. 

Cos.  0  =  0. 7071  ;    the    sin.   20  =  1.0000;    and  a— 1.148;      —  == 

2 

1.148.262.0.7071  aVi  .         j       1.148.262    ,  _^ 

=  0.1490  ;  p=  — sin.2  0  =  —  »  •      „.     1.0000  = 

1427  '  l         gc  Y    32.17.4677 

0.5238  from  table  (4)  --=0.4412  ;  X= — =1798  feet. 

v        c  '  1.148 

The  slight  discrepancies  in  these,  as  in  the  preceding 
results,  arise  from  the  neglected  decimals. 

425.  Comparison  of  true  and  calculated  trajectories. 

In  consequence  of  considering  the  inclination  of  the  tra- 
jectory as  constant  in  the  preceding  equations,  the  re- 
sistance of  the  air  is  slightly  underestimated  in  the 
more  inclined  portions  of  the  trajectory,  or  at  the  be- 
ginning and  end,  and  slightly  overestimated  in  the  less 
inclined  portions,  or  about  the  summit.  It  follows  that 
the  calculated  trajectory  will  at  first  rise  above  the  true 
one,  then  pass  below  it,  and  again  pass  above  it ;  the 
calculated  ranges  will  therefore  be  found  slightly  in 
excess. 

426.  Trajectory  of  oblong  projectile.     From  the  law 


424    SCIENCE  OF  GUNNERY. DEVIATION  OF  PROJECTILES. 

of  inertia,  a  rifle  projectile  moves  through  the  air  with 
its  axis  of  rotation  parallel  to  the  axis  of  the  bore. 
Hence,  it  follows,  that  an  oblong  projectile,  fired  under 
a  low  angle  of  projection,  presents  a  greater  surface  to- 
ward the  earth,  and  less  parallel  to  it,  than  a  round 
projectile  of  the  same  weight ;  consequently  the  vertical 
component  of  the  resistance  of  the  air  is  greater,  and 
the  horizontal  component  less,  in  the  first  case  than  in 
the  second.  The  effect  of  this  will  be  to  give  an  oblong 
projectile  a  flatter  trajectory  and  longer  range  than  a 
round  one. 

DEVIATION  OF  PROJECTILES. 

427.  Nature  and  cau§e§.  The  path  described  by  the 
centre  of  inertia  of  a  projectile,  moving  under  the  influ- 
ence of  gravity  and  the  tangential  resistance  of  the  air, 
is  called  the  normal  trajectory  /  and  it  is  this  trajectory 
which  has  been  the  subject  of  the  preceding  discussions. 
In  practice,  various  causes  are  constantly  at  work  to 
deflect  a  projectile  from  its  normal  path,  and  it  becomes 
necessary  to  study  the  nature  of  these  causes,  and  their 
effects. 

All  deviating  causes  may  be  divided  into  two  classes 
— those  which  act  while  the  projectile  is  in  the  bore  of 
the  piece,  and  those  which  act  after  the  projectile  has 
left  it.  The  first  class  includes  all  the  causes  which 
affect  the  initial  velocity,  and  give  rotation  to  the  pro- 
jectile ;  the  second  includes  the  action  of  the  air. 

428.  Causes  which  affect  initial  velocity.  The  princi- 
pal causes  which  affect  initial  velocity  are  variations  in 
the  weights  of  the  powder  and  projectile,  the  manner 


ROTATION.  425 

of  loading,  the  temperature  of  the  piece,  and  the  ballot- 
ing of  the  projectile  along  the  bore.  Experiments  made 
by  firing  siege  and  field  projectiles  into  the  ballistic  pen- 
dulum, show  that,  with  care,  the  mean  variation  in  the 
initial  velocity,  in  a  series  of  fires,  doe3  not  exceed  20  feet. 

A  variation  of  20  feet  in  initial  velocity  only  produ- 
ces a  variation  of  £  a  foot,  in  the  vertical  height  of  the 
trajectory  of  a  12-pdr.  ball,  at  a  distance  of  1,000  yards. 

429.  Rotation.  The  principal  cause  of  the  deviation 
of  a  projectile  is  its  rotation  combined  with  the  resist- 
ance of  the  air.  It  is  proposed,  in  the  first  place,  to 
show  how  rotation  may  be  produced,  and,  in  the  sec- 
ond, to  show  how  rotation,  combined  with  the  resist- 
ance of  the  air,  produces  deviation. 

By  balloting.  If  the  projectile  be  spherical  and  ho- 
mogeneous, rotation  is  produced  by  the  bounding  or 
balloting  of  the  ball  in  the  bore,  arising  from  the  wind- 
age. In  this  case  the  axis  of  rotation  is  horizontal,  and 
passes  through  the  centre  of  the  ball ;  the  direction 
of  rotation  depends  on  the  side  of  the  projectile  which 
strikes  the  surface  of  the  bore  last ;  if  it  strike  on  the 
upper  side,  the  front  surface  of  the  projectile  will  move 
upward;  if  on  the  lower  side,  this  surface  will  move 
downward. 

The  velocity  of  rotation  from  this  cause  depends  on 
the  windage,  or  depth  of  the  indentations  in  the  bore, 
the  charge  being  the  same.  It  has  been  found  to  be, 
for  ordinary  windage,  about  30  feet  for  a  24-pdr.  shell 
fired  with  2f  lbs  of  powder. 

By  eccentricity.  If,  from  the  structure  of  the  ball, 
or  from  some  defect  of  manufacture,  the  centre  of  grav- 
ity do  not  coincide  with  the  centre  of  figure,  rotation 


426    SCIENCE  OF  GUNNERY. DEVIATION  OF  PROJECTILES. 

generally  takes  place  around  the  centre  of  gravity. 
This  arises  from  the  fact  that  the  resultant  of  the 
charge  acts  at  the  centre  of  figure,  while  inertia,  or  re- 
sistance to  motion,  acts  at  the  centre  of  gravity.  The 
axis  of  rotation  passes  through  the  centre  of  gravity, 
and  is  perpendicular  to  a  plane  containing  the  resultant 
of  the  charge  and  the  centres  of  figure  and  gravity.  For 
the  same  charge,  the  velocity  of  rotation  is  proportional 
to  the  lever  arm,  or  perpendicular,  let  fall  from  the  cen- 
tre of  gravity  to  the  resultant  of  the  charge. 

Knowing  the  position  of  the  centre  of  gravity  of  the 
ball  in  the  bore,  it  is  easy  to  foretell  the  direction  and 
velocity  of  rotation.  In  general  terms,  the  front  surface 
of  the  projectile  moves  toward  the  side  of  the  bore  on 
which  the  centre  of  gravity  is  situated,  and  the  velocity 
of  rotation  is  greatest  when  the  line  joining  the  centres 
of  gravity  and  figure  is  perpendicular  to  the  axis  of 
the  bore. 

The  position  of  the  centre  of  gravity  of  a  projectile 
is  found  by  floating  in  a  mercury  bath ;  and  by  an  in- 
strument called  the  eccentrometer.  The  topmost  point 
of  the  surface,  when  the  projectile  has  settled  to  a  state 
of  rest  in  the  bath,  marks  one  point  at  which  the  line 
joining  the  centre  of  gravity  and  figure  pierces  the  sur- 
face ;  the  position  of  the  centre  of  gravity  along  this 
line  is  determined  by  the  eccentrometer,  which  is  a  pe- 
culiar kind  of  balance.  w  being  the  weight  of  the 
projectile,  and  x  the  distance  of  its  centre  of  gravity 
from  the  fulcrum  of  the  balance,  and  w  being  the  weight 
necessary  to  balance  the  projectile,  and  a  its  distance 
from  the  fulcrum,  we  have,  from  the  equality  of  the 
moments— 


THE    EFFECT    OF    KOTATION.  427 


.                       aw 
aw  =zw%.  or  x=. 


w 

The  position  of  the  projectile  on  the  balance  being 
known,  by  placing  the  marked  point  on  the  surface 
nearest  the  fulcrum,  the  position  of  the  centre  of  grav- 
ity becomes  known;  for  if  b  be  the  distance  of  the 
marked  point  from  the  fulcrum,  and  r  the  radius  of  the 
projectile,  x—b—r  is  the  distance  between  the  centres 
of  gravity  and  figure. 

430.  The  effect  of  rotation.  The  effect  of  rotation  in 
producing  deviation,  may  be  studied  under  three  heads: 
1st.  When  the  projectile  is  spherical  and  concentric. 
2d.  When  it  is  spherical  and  eccentric;  and  3d.  When 
it  is  oblong. 

Concentric  projectiles.  The  simplest  case  is  that  of  a 
homogeneous  spherical  projectile,  rotating  around  a  ver- 
tical axis  passing  through  the  centre  of  gravity. 

Let  A  B  0  D  represent  the  great  circle  cut  out  of 
the  sphere  perpendicular  to  the  axis  of  rotation,  and 
suppose  rotation  to  take  place 
in  the  direction  A  C  B,  and  the 
motion  of  translation  in  the  di- 
rection A  B ;  it  is  evident  that 
each  point  of  the  circle  moves 
in  the  direction  A  B,  with  a  ve-  Fig.  iSS! 

locity  which  is  equal  to  the  velocity  of  translation,  plus 
or  minus  the  component  of  its  velocity  of  rotation  in 
the  direction  of  the  axis  A  B,  which  is  equal  to  the 
projection  of  the  arc  over  which  the  point  moves  in  a 
unit  of  time,  on  the  line  A  B.  The  points  <7and  D 
have  the  greatest  velocity  in  the  direction  of  this  line, 
A  B,  and  the  points  A  and  B  the  least.     All  the  points 


428     SCIENCE  OF  GUNNERY. DEVIATION  OF  PROJECTILES. 

in  the  semi-circle  A  C  B  rotate  in  a  forward  direction, 
and  the  components  of  their  velocities  of  rotation  must 
be  added  to  that  of  translation ;  while  the  points  in  the 
semicircle  B  D  A  move  backward  in  rotation,  and  the 
components  of  their  velocities  must  be  subtracted  from 
it.  A  body  moving  in  the  air  draws  with  it  a  film  of 
the  particles  which  surround  it,  and  these  particles  set 
in  motion  the  adjacent  particles,  and  so  on  from  one 
layer  to  another ;  the  number  of  particles  set  in  motion 
and  their  reaction  on  the  surface  of  the  projectile,  de- 
pend on  the  velocity  of  the  moving  surface;  now  it  has 
been  shown  that  the  surface  A  O  B  moves  with  a 
greater  velocity  than  the  opposite  side,  the  reaction,  or 
pressure  upon  it,  must  be  greater  than  upon  the  latter, 
and  the  projectile  will  be  urged  in  the  direction  C  D. 
Eccentric  projectiles.  Let  A  G  B  D  represent  the 
great  circle  cut  out  of  an  eccen- 
tric projectile  perpendicular  to 
the  axis  of  rotation,  and  contain- 
ing the  centre  of  figure  O,  and 
the  centre  of  gravity  O'.  Sup- 
pose the  motions  of  rotation  and 
Fis- 139-  translation  to  take  place    as  in 

the  preceding  case,  it  follows  that  the  same  cause  will 
operate  in  this,  as  in  the  preceding  case,  to  deviate  the 
projectile  in  the  direction  CD;  but  there  is  another 
and  more  powerful  cause  operating  to  deviate  the  pro- 
jectile in  the  same  direction,  and  that  is,  the  greater 
pressure  on  the  side  A  C  B  arising  from  the  greater 
surface  offered  to  the  air  in  consequence  of  the  eccen- 
tricity. 

Prof.  Magnus1  apparatus.     These  phenomena  may  be 


THE  EFFECT  OF  ROTATION.  429 

easily  illustrated  by  the  very  simple  and  ingenious  ap- 
paratus devised  by  Prof.  Magnus,  of  Berlin.  Let  C 
(fig.  140)  represent  a  light  brass  cylinder,  delicately 
susj>ended   in    a    ring,  and   made   to   revolve   rapidly 

around    its    vertical    axis,    by 

means  of  a  string,  after  the  man- 

ner  of  a  top ;  let  this  ring   be 

suspended  at  the  extremity  of 

a  wooden    lever  I>\  which,  in 

turn,  is  suspended  by  a  delicate 

wire  from  the  ceiling,  so  that  it 

may  rotate  freely  in  a  horizontal  direction  ;  let  Pbea 

counterpoise,  and  R  the  direction  of  a  strong  current 

of  air  blowing  upon  the  cylinder  from  a  fan-blower. 

It  is  invariably  found,  that  the  axis  of  the  cylinder 
will  move  in  the  opposite  direction  from  the  side  which 
is  moving  toward  the  current  of  air  from  the  blower 
(see  direction  of  the  arrows) ;  but  if  there  be  no  rota- 
tion of  the  cylinder,  the  axis  will  remain  stationary. 

Conclusions.  If  a  projectile  be  spherical  and  concen- 
tric, rotation  takes  place  from  contact  with  the  surface 
of  the  bore  around  a  horizontal  axis,  and  the  effect  will 
be  to  shorten  or  lengthen  the  range,  as  the  motion  of 
the  front  surface  is  downward  or  upward. 

If  the  projectile  be  eccentric,  the  motion  of  the  front 
surface  is  generally  toward  the  side  on  which  the 
centre  of  gravity  is  situated,  and  the  deviation  takes 
place  in  this  direction. 

The  extent  of  the  deviation  for  the  same  charge,  de- 
pends on  the  position  of  the  centre  of  gravity;  the 
horizontal  deviation  being  the  greatest  when  the  centres 
of  gravity  and  figure  are  in  a  horizontal  plane,  and  the 


430     SCIENCE  OF  GUNNERY. DEVIATION  OF  PROJECTILES. 

line  which  joins  them  is  at  right  angles  to  the  axis  of 
the  piece ;  the  vertical  deviation  will  be  the  greatest 
when  these  centres  are  in  a  vertical  plane,  and  the  line 
which  joins  them  is  at  right  angles  to  the  axis  of  the 
piece.  If  the  axis  of  rotation  coincide  with  the  tangent 
to  the  trajectory  throughout  the  flight,  all  points  of  the 
surface  have  the  same  velocity  in  the  direction  of  the 
motion  of  translation,  and  there  will  be  no  deviation. 
This  explains  why  it  is  that  a  rifle-projectile  moves 
through  the  air  more  accurately  than  a  projectile  from 
a  smooth-bored  gun. 

In  the  experiments  of  Major  Wade  with  32-pdr.  field- 
shells,  made  purposely  eccentric,  the  difference  of  the 
extreme  lateral  deviations,  produced  by  placing  the 
centre  of  gravity  first  on  one  side  and  then  on  the  other, 
amounted  to  100  yds.,  or  one-fourth  of  the  entire  range. 

The  experiments  of  Captain  Dahlgren  with  service  32- 
pdr.  balls,  show  the  following  results  when  the  centre 
of  gravity  is  placed  in  different  positions  in  the  verti- 
cal plane  through  the  axis  of  the  bore. 


POSITION    OF    CENTRE    OF    QRAVITY    IN    VERTICAL    PLANE. 

90°  up. 

90°   down. 

Inward. 

45°  up.  and  in. 

1415  yds. 

1264  yds. 

1329  yds. 

1360  yds. 

In  accurate  firing,  therefore,  it  is  important  to  know 
the  true  position  of  the  centre  of  gravity :  in  ricochet 
firing  over  smooth  water,  the  number  of  grazes  may  be 
increased  or  diminished  by  placing,  in  loading,  the  cen- 
tre of  gravity  above  or  below  the  centre  of  figure. 

The  first  person  to  call  attention  to  the  deviation 


DEVIATION    OF    OBLONG    PROJECTILES.  431 

produced  by  rotation,  was  Kobins,  who  illustrated  it  by 
bending  a  musket-barrel  to  the  right,  and  firing  through 
a  succession  of  paper  screens ;  the  projectile  was  observed 
to  deviate,  first  to  the  right,  in  the  direction  in  which 
the  muzzle  was  pointed,  and  then  to  the  left,  in  the 
opposite  direction  from  the  side  of  the  projectile  which 
rotates  toward  the  front. 

431.  deviation  of  oblong  projectiles.  The  cause  of 
the  deviation  of  an  oblong  rifle  pro- 
jectile is  quite  different  from  one  of 
spherical  form.  An  oblong  projec- 
tile moving  in  the  air  is  acted  upon 
Pig.  141.  Dy  two  rotary  forces,  viz. ;  one  which 

gives  it  its  normal  rotary  motion  around  its  axis  of  pro- 
gression, and  another  the  resistance  of  the  air,  which,  in 
consequence  of  the  deflection  of  the  axis  of  progression 
from  the  tangent  to  the  trajectory  by  the  action  of  grav- 
ity, does  not  pass  through  the  centre  of  inertia,  but 
above  or  below  it,  depending  on  the  shape  of  the  pro- 
jectile. From  a  law  of  mechanics,  a  body  thus  circum- 
stanced, will  not  yield  fully  to  either  of  the  forces  that 
thus  act  upon  it,  but  its  apex  will  move  off  with  a 
slow  uniform  motion  to  the  right  or  left  of  the  vertical 
plane,  depending  on  the  relative  direction  of  the  two 
rotary  forces.  If  the  action  of  these  forces  be  contin- 
ued sufficiently  long,  it  will  be  seen  that  the  axis  of  the 
projectile  before  referred  to,  describes  a  cone  around  a 
line  passing  through  the  centre  of  inertia  and  parallel 
to  the  direction  of  the  resistance  of  the  air. 

Owing  to  the  short  duration  of  the  flight  of  an  ordi- 
nary projectile,  it  is  only  necessary  to  consider  the  first 
part  of  this  conical  motion.    If  the  projectile  rotates  in 


432     SCIENCE  OF  GUNNEKY. DEVIATION  OF  PEOJECTILES. 

the  direction  of  the  hands  of  a  watch  to  the  eye  of  the 
marksman,  and  the  resultant  of  the  resistance  of  the  air 
pass  above  the  centre  of  inertia,  as  it  does  in  the  service 
bullet  with  a  conoidal  point,  see  fig.  141,  then  the  point 
of  the  projectile  will  move  to  the  right,  which  brings 
the  left  side  of  the  projectile  obliquely  in  contact  with 
the  current  of  the  air.  The  effect  of  this  position  with 
reference  to  the  air,  will  be  to  generate  a  component 
force  that  will  urge  the  projectile  to  the  right  of  the 
plane  of  fire,  as  a  vessel  sailing  on  the  wind  has  a  mo- 
tion to  the  leeward. 

If  the  bore  be  grooved  with  a  left-handed  twist,  the 
deviation  will  be  to  the  left  of  the  plane  of  fire,  as  has 
been  shown  by  actual  experiment.  This  peculiar  devi- 
ation was  called  by  the  French  officers  that  first  observed 
it,  "  derivation"  or  "  drift."  That  it  is  not  produced  by 
the  effect  of  the  recoil  on  the  shoulder  of  the  marksman, 
1  as  some  assert,  is  shown  by  the  fact  that  drift  increases 
more  rapidly  than  the  distance. 

The  following  table  gives  the  drift  at  different  dis- 
tances, for  the  French  rifle,  model  of  1842,  with  a  twist 
of  4.37  feet,  and  a  bullet  with  a  single  groove : 


Distances  in 
yards. 

218 

328 

437 

546 

656 

165 

874 

984 

1093 

1312 

1421 

Drift  in  feet 
and  inches. 

.5" 

l'.l" 

1'.9" 

1 
2'.0"U'.9" 

7'.6" 

11'.6" 

16'.1" 

21'.0" 

38'.4" 

50'.6" 

In  consequence  of  the  reduced  calibre  and  twist,  the 
drift  of  our  present  rifle-musket  projectiles  is  less  than 
the  foregoing.  The  mean  drift  of  40  shots  fired  from 
two  service  rifle-muskets,  at  a  distance  of  1,150  yds.,  in 


SUMMARY    OF    DEVIATING    CAUSES.  433 

a  perfectly  calm  day,  was  about  18  feet;   not  a  single 
shot  deviated  to  the  left  of  the  point  aimed  at.* 

432.  Effect  of  wind.  The  deviating  effect  of  wind 
depends  on  its  force,  and  its  direction  with  regard  to 
the  plane  of  fire ;  generally  speaking,  large  and  heavy 
projectiles,  moving  with  high  velocities,  are  deviated 
less  than  those  of  contrary  character.  It  is  difficult  to 
calculate  the  effect  of  the  wind  in  any  particular  case ; 
in  making  allowance  for  it,  therefore,  the  gunner  should 
be  guided  by  experience  and  judgment.  For  the  same 
projectile,  velocity,  and  wind,  the  deviation  varies  nearly 
as  the  square  of  the  range. 

433.  Summary  of  deviating  causes.  The  following 
summary  may  be  considered  as  embracing  nearly  all  the 
causes  of  deviation  of  cannon  and  small-arm  projectiles. 

1st.  From  the  construction  of  the  piece.  These  causes 
are,  wrong  position  of  the  sight ;  bore  not  of  the  true 
size;  crooked  barrel;  too  hard  on  the  trigger;  wind- 
age ;  the  recoil ;  and  spring  of  the  barrel. 

2d.  From  the  charge  of  powder.  Improper  weight; 
form  of  grain  and  variable  quality  of  the  powder ;  in- 
jury from  dampness;  more  or  less  ramming;  sticking 
along  the  bore  from  foulness  and  dampness. 

3d.  From  the  projectile.  Not  of  the  exact  size,  shape, 
or  weight ;  disfiguration  in  loading,  or  on  leaving  the 
bore;  eccentricity. 

4th.  From  the  atmosphere,  &c.  The  effect  of  wind ; 
variations  in  the  temperature,  moisture,  and  density  of 

*  The  subject  of  drift  has  been  fully  exposed  in  a  learned  analytical  investigation  by 
General  Barnard,  of  the  engineer  corps,  who  shows  that  it  is  a  particular  case  of  the 
gyroscope.  It  has  also  been  explained  experimentally  by  Professor  Magnus,  of  Berlin, 
a  copy  of  whose  apparatus  may  be  found  in  the  Museum  of  the  United  States  Mili- 
tary Academy. 

28 


434     SCIENCE  OF  GUNNERY. DEVIATION  OF  PROJECTILES. 

the  air;  position  of  the  sun  as  regards  the  effect  on 
the  aim;  difference  of  level  between  the  object  and 
piece ;  and  rotation  of  the  earth. 

The  latter  source  of  deviation  arises,  1st.  From  the 
fact  that  all  points  on  the  surface  of  the  earth,  not  in 
the  same  parallel  of  latitude,  move  with  different  angu- 
lar velocities;  and  2d.  That  when  a  body  is  thrown 
from  one  point  to  another,  it  carries  with  it  the  angu- 
lar velocity  with  which  it  started.  Applying  these 
facts,  it  is  found  that  a  projectile  will  deviate  to  the 
right  of  the  object,  whatever  may  be  the  direction  of 
the  line  of  fire,  and  at  a  distance  from  it,  depending  on 
the  latitude  of  the  place,  and  on  the  time  of  flight  and 
the  range  of  the  projectile. 

Poisson  has  shown  that  a  12-inch  shell  weighing 
200  lbs.,  fired  under  an  angle  of  45°,  with  an  initial 
velocity  of  900  feet,  will  deviate  from  15  to  20  feet  to 
the  right  of  the  object — the  range  being  about  4,400 
yards. 


USE  OF  PROJECTILES  NOT  SUITED  TO  THE  BORE.      435 


CHAPTER    IX. 

LOADING,  POINTING,  AND  DISCHARGING  FIRE- 
ARMS. 

434.  Loading.  In  loading  guns  and  howitzers,  the 
powder  is  carefully  put  up  in  a  cartridge-bag  of  woollen 
cloth,  which  is  either  attached  to,  or  carried  separate 
from  the  projectile,  depending  on  the  weight  of  the 
projectile.  In  ramming  a  charge,  only  a  sufficient  force 
should  be  used  to  send  it  home,  as  the  space  which  the 
powder  occupies  affects  the  initial  velocity.  In  loading 
mortars,  the  powder  is  poured  from  the  cartridge-bag 
into  the  chamber,  and  levelled  with  the  hand ;  the  shell 
is  then  carefully  lowered  upon  it  with  the  hooks. 

435.  Precautions.  After  a  piece  has  been  discharged 
the  bore  should  be  well  sponged,  to  extinguish  any 
burning  fragments  of  the  cartridge  that  may  remain ; 
and  to  prevent  the  current  of  air  from  fanning  any 
burning  fragments  that  may  collect  in  the  vent,  it 
should  be  kept  firmly  closed  with  a  thumb-stall  in  the 
operation  of  sponging.  Experience  shows  that  the  use 
of  a  wet  sponge  is  dangerous,  as  it  contributes  to  form, 
from  the  fragments  of  the  cartridge-bag,  a  substance 
which  retains  fire. 

436.  Use  of  projectiles  not  suited  to  the  bore.  It  may 
be  sometimes  necessary  to  fire  projectiles  that  are  either 
very  much  smaller  or  larger  than  the  bore. 

If  it  be  desired  to  use  a  gun-shell,  or  solid  shot,  which 


436  LOADING   AND    POINTING    FIKE-AKMS. 

is  much  smaller  than  the  bore,  it  is  strapped  to  a  stout 
sabot  which  fits  the  bore  ;  if  a  mortar-shell,  it  is  placed 
in  the  centre  of  the  bore  by  means  of  wedges,  and  the 
surrounding  space  is  filled  up  with  earth. 

Mortar-shells  are  fired  from  guns  and  howitzers,  by 
digging  a  hole  in  the  ground  about  20  inches  deep,  and 
placing  in  it  two  pieces  of  stout  plank  inclined  at  an 
angle  of  45°,  for  the  support  of  the  breech ;  the  chase 
is  supported  on  a  movable  wedge,  which  rests  on  skids 
firmly  secured  with  platform  stakes;*  the  charge  of 
powder  is  then  inserted  in  the  bore,  and  the  projectile 
is  placed  on  the  muzzle,  and  secured  by  passing  strings 
over  it,  and  tying  their  ends  to  a  rope,  which  encircles 
the  neck  of  the  chase. 

Pieces  fired  in  this  way  should  be  elevated  40°  or 
45°;  thus  situated,  the  fuze  of  the  8-inch  mortar-shell 
takes  fire  from  very  small  charges ;  but  the  10-inch  fuze 
should  be  primed  with  strands  of  quick-match,  which 
are  allowed  to  hang  over  the  sides  of  the  shell. 

POINTING. 

To  point  or  aim  a  fire-arm  is,  to  give  it  such  direction 
and  elevation  that  the  projectile  shall  strike  the  object. 
To  do  this  properly,  it  is  necessary  to  understand  the 
relations  which  exist  between  the  line  of  sight,  line  of 
fire,  trajectory,  &c. 

437.  I>eflnition§.  The  line  of  sight  is  the  right  line 
containing  the  guiding  points  of  the  sights.  The  sights 
are  two  pieces,  A  and  B,  on  the  upper  surface  of  the 

*  Pieces  that  have  been  disabled  by  breaking  off  a  trunnion,  may  be  fired  in 
this  manner. 


DEFINITIONS.  437 


Fig.  142. 

gun,  the  situation  of  which  with  regard  to  the  axis  of 
the  bore  is  known.  The  front  sight  is  situated  near  the 
muzzle,  or  on  the  right  rimbase,  and  is  generally  fixed ; 
the  rear  sight  is  placed  near  the  breech-sight,  and  is 
movable  in  a  vertical,  and  sometimes  in  a  horizontal  di- 
rection. The  natural  line  of  sight  is  the  line  of  sight 
nearest  the  axis  of  the  piece ;  the  others  are  called  arti- 
ficial lines  of  sight. 

The  line  of  fire  is  the  axis  of  the  bore  prolonged  in 
the  direction  of  the  muzzle,  or  CD. 

The  angle  of  fire  is  the  angle  included  between  the 
line  of  fire  and  horizon;  on  account  of  the  balloting 
of  the  projectile,  the  angle  of  fire  is  not  always  equal 
to  the  angle  of  departure,  or  projection.  See  section 
268. 

The  angle  of  sight  is  the  angle  included  between 
the  line  of  sight  and  line  of  fire ;  angles  of  sight  are 
divided  into  natural  and  artificial  angles  of  sight,  cor- 
responding to  the  natural  and  artificial  lines  of  sight 
which  enclose  them. 

The  plane  of  fire  is  the  vertical  plane  containing  the 
line  of  fire. 

The  plane  of  sight  is  the  vertical  plane  containing  the 
line  of  sight. 

The  point-blank  is  the  point  at  which  the  line  of  sight 
insersects  the  trajectory,  or  P.  Strictly  speaking,  the 
line  of  sight  intersects  the  trajectory  at  two  points,  C 


438  LOADING    AND    POINTING    FIRE-ARMS. 

and  P  /  but,  in  practice,  the  j)oint  P  is  only  considered. 
The  distance,  B  P,  is  called  the  point-blank  distance. 

The  natural  point-blajik  corresponds  to  the  natural 
line  of  sight ;  all  other  point-blanks  are  called  artificial 
point-blanks.  In  speaking  of  the  point-blank  of  a 
piece,  the  natural  line  of  sight  is  supposed  to  be  hori- 
zontal. 

In  the  British  service,  the  point-blank  distance  is  the 
distance  at  which  the  projectile  strikes  the  level  ground 
on  which  the  carriage  stands,  the  axis  of  the  piece  be- 
ing horizontal.  It  is  evident  that  this  definition  of 
point-blank  distance  conveys  a  better  idea  of  the  power 
of  the  piece  than  the  former,  which  makes  it  depend  on 
the  form  of  the  piece,  as  well  as  on  the  charge. 

As  the  angle  of  sight  A  C  C  is  increased,  the  point- 
blank  distance  is  increased ;  as  it  is  diminished,  the  in- 
tersections of  the  line  of  sight  and  trajectory  approach 
each  other  until  they  unite,  when  the  line  of  sight  and 
trajectory  are  tangent  to  each  other ;  beyond  this,  the 
point-blank  is  imaginaiy. 

As  the  angle  of  fire  increases,  the  force  of  gravity 
acts  more  in  opposition  to  the  force  of  projection,  and 
the  point-blank  distance  is  diminished,  until  at  90°  it 
becomes  zero.  Under  an  angle  of  depression,  the  force 
of  gravity  acts  more  nearly  in  the  direction  of  gravity, 
and  the  point-blank  distance  is  increased,  becoming  in- 
finite when  the  angle  of  depression  is  equal  to  90°  minus 
the  angle  of  sight. 

In  ordinary  firing,  it  is  not  considered  that  the  trajec- 
tory changes  its  position  with  reference  to  the  lines  of 
sight  and  fire,  for  angles  of  elevation  and  depression, 
less  than  15°.     In  aiming  at  an  object,  therefore,  the 


POINTING    GUNS    AND    HOWITZERS.  439 

angle  of  elevation  of  which  is  less  than  15°,  aim  as  though 
it  were  in  the  same  horizontal  plane  with  the  piece. 

For  the  same  piece,  the  point-blank  distance  in- 
creases with  the  charge  of  powder;  for  the  same 
initial  velocity,  a  large  projectile  has  a  greater  point- 
blank  distance  than  a  small  one ;  a  solid  shot  than  a 
hollow  one ;  an  oblong  projectile  than  a  round  one  ;  or, 
in  other  words,  it  varies  with  the  value  of  c,  before  re- 
ferred to. 

Range  is  the  distance  at  which  a  projectile  first 
strikes  the  ground  on  which  the  carriage  is  situated ; 
extreme  range  is  the, distance  to  the  point  at  which  the 
projectile  is  brought  to  a  state  of  rest. 
;  438.  Pointing  guns  and  howitzers.  In  pointing 
2-  «*  guns  and  howitzers  under  ordinary  angles  of  elevation, 
&*•»•  the  piece  is  first  directed  toward  the  object,  and  then 
elevated  to  suit  the  distance.  The  accuracy  of  the  aim 
depends — 1st.  On  the  fact  that  the  object  is  situated  in 
the  plane  of  sight;  2d.  That  the  projectile  moves  in 
the  plane  of  fire,  and  that  the  planes  of  sight  and  fire 
coincide,  or  are  parallel  and  near  to  each  other;  and 
3d.  On  the  accuracy  of  the  elevation. 

The  first  of  these  conditions  depends  on  the  eye  of 
the  gunner,  and  the  accuracy  and  delicacy  of  the  sights ; 
the  errors  under  this  head  are  of  but  little  practical  im- 
portance. 

When  the  trunnions  of  the  piece  are  horizontal,  and 
the  sights  are  properly  placed  on  the  surface  of  the 
piece,  the  planes  of  sight  and  fire  will  coincide;  but 
when  the  axis  of  the  trunnions  is  inclined,  and  the 
natural  line  of  sight  is  oblique  to  the  axis  of  the  bore, 
the  planes  are  neither  parallel  nor  coincident,  and  the 


^4 


440  LOADING    AND    POINTING    FIRE-ARMS. 

aim  will  be  incorrect.  If  the  natural  line  of  sight  be 
made  parallel  to  the  line  of  fire,  by  making  the  height 
of  the  front  sight  equal  to  the  dispart  of  the  piece,  the 
planes  of  sight  and  fire  will  be  parallel,  and  at  a  dis- 
tance from  each  other  equal  to  the  radius  of  the  breech 
multiplied  by  the  sine  of  the  angle  which  the  axletree 
makes  with  the  horizon.  To  show  this,  let  the  circle 
A  C  B  D  represent  the  section  of  the  breech  of  the 
piece  taken  at  right  angles  to  the  axis, 
and  C  the  projection  of  the  natural 
line  of  sight  upon  this  plane;  let  A' 
B'  be  the  inclined  position  of  the 
axletree,  or  trunnions,  C  marks  the 
revolved  position  of  the  natural  line 
Fig-  143'  of  sight,  and  C  D'  the  trace  of  the 

plane  of  sight,  which  is  parallel  to  C  Z>,  the  trace  of  the 
plane  of  fire.  As  the  lines  of  sight  and  fire  are  paral- 
lel in  their  revolved  position,  the  planes  of  sight  and 
fire  must  also  be  parallel.  The  angle  COC'  =  BOB\ 
therefore  CC'=  OC'  sin.  BOB',  It  is  easily  seen  that 
with  this  arrangement  of  the  front  sight,  the  error  of 
pointing  can  never  exceed  the  radius  of  the  breech. 
By  an  inspection  of  the  figure,  it  will  also  be  seen,  that 
in  the  revolved  position  of  the  line  of  sight,  the  eleva- 
tion is  diminished  by  a  small  quantity,  which  is  equal 
to  the  versed  sine  of  the  arc  CO. 

By  referring  to  the  construction  of  the  pendulum 
hausse,  on  page  255,  we  see  that  if  its  centre  of  motion 
coincide  with  the  point  C\  and  the  scale  coincide  with 
the  line  C  JD',  the  error  of  aiming  with  an  artificial 
line  of  sight  is  practically  no  greater  than  with  the 
natural  line  of  sight. 


POINTING    GUNS    AND    HOWITZERS.  441 

If  the  natural  line  of  sight  be  not  parallel  to  the 
axis  of  the  piece,  the  planes  of  sight  and  fire  intersect 
at  a  short  distance  from  the  muzzle ;  hence,  it  follows, 
that  as  the  object  is  situated  in  the  plane  of  sight,  the 
projectile  will  deviate  from  the  object  to  the  side  on 
which  the  lower  wheel  is  situated,  and  at  a  distance 
from  it,  which  is  proportional  to  the  distance  of  the 
object  from  the  piece;  to  correct  for  this  source  of 
error,  the  line  of  sight  should  be  pointed  to  the  side 
of  the  higher  wheel,  and  at  a  distance  from  the  object, 
which  is  proportional  to  the  distance  of  the  object 
from  the  piece. 

Siege  and  sea-coast  cannon  are  generally  fired  from 
fixed  platforms,  which  renders  the  axis  of  the  trunnions 
horizontal ;  they  are,  therefore,  not  furnished  with  pen- 
dulum sights. 

In  case  the  axis  of  the  trunnions  is  not  horizontal, 
and  the  piece  has  not  a  pendulum  hausse,  the  highest 
points  of  metal  at  the  breech  and  muzzle  may  be  de- 
termined by  the  gunner's  level  (see  page  254),  and 
marked  with  chalk ;  the  centre  line  of  the  tangent 
scale,  or  breech-sight,  is  placed  on  the  mark  at  the 
breech,  the  slider  is  placed  at  the  proper  elevation,  and 
the  aim  is  taken  along  the  notch  of  the  slider  and  the 
mark  on  the  muzzle.  This  method,  however,  does  not 
give  a  perfectly  accurate  aim. 

In  the  absence  of  a  breech-sight,  the  piece  can  be 
pointed  with  the  natural  line  of  sight  so  as  to  strike 
objects  not  situated  at  point-blank  distance;  if  the 
object  be  within  point-blank  range,  as  at  P"  (fig. 
142),  the  natural  line  of  sight  should  be  depressed  be- 
low the  object  as  much  as  the  trajectory  is  above  it ;  if 


442  LOADING   AND    POINTING   FIRE-ARMS. 

it  be  beyond  point-blank,  as  at  P\  the  natural  line  of 
sight  should  be  directed  to  a  point  JI,  which  is  as  much 
above  the  object,  as  the  point  H\  of  the  trajectory,  is 
below  it. 

Owing  to  the  shape  and  size  of  the  reinforce  of  sea- 
coast  cannon,  the  natural  line  of  sight  is  formed  by 
affixing  a  front  sight  to  the  muzzle,  or  to  a  projection 
cast  on  the  piece  between  the  trunnions.  Although 
the  latter  arrangement  does  not  give  quite  so  long  a 
distance  between  the  sights  as  is  desirable,  it  permits 
the  use  of  a  shorter  breech-sight,  and  the  front  sight 
does  not  interfere  with  the  roof  of  the  embrasure,  when 
the  piece  is  fired  under  high  elevation. 

439.  Pointing  mortars  and  small-arm§.  In  pointing 
small-arms  and  mortars,  the  piece  is  first  given  the  ele- 
vation, and  then  the  direction  necessary  to  attain  the 
object. 

Pointing  mortars.  Mortars  are  generally  fired  from 
behind  epaulements,  which  screen  the  object  from  the 
eye  of  the  gunner. 

The  elevation  is  first  given  by  a  gunner's  quadrant, 
applied  as  described  on  page  256 ;  and  the  direction  is 
given  by  moving  the  mortar-bed  with  a  handspike,  so  as 
to  bring  the  line  of  sight  into  the  plane  of  sight,  which, 
by  construction,  passes  through  the  object  and  the  cen- 
tre of  the  platform.  The  plane  of  sight  may  be  deter- 
mined in  several  ways;  the  method  prescribed  is  to 
plant  two  stakes,  one  on  the  crest  of  the  epaulement,  and 
the  other  a  little  in  advance  of  the  first,  so  that  the  two 
shall  be  in  a  line  with  the  object,  and  the  gunner  stand- 
ing in  the  middle  of  the  rear-edge  of  the  platform ;  a 
cord  is  attached  to  the  second  stake,  and  held  so  as  to 


POINTING    MORTARS    AND    SMALL-ARMS.  443 

touch  the  first  stake ;  a  third  stake  is  driven  in  a  line 
with  the  cord,  in  rear  of  the  platform,  and  a  plummet 
is  attached  to  this  cord  so  as  to  fall  a  little  in  rear  of 
the  mortar.  It  is  evident  that  the  cord  and  plummet 
determine  the  required  plane  of  sight  into  which  the 
line  of  sight  of  the  mortar  must  be  brought. 

The  usual  angle  of  fire  of  mortars  is  45°,  which  cor- 
responds nearly  with  the  maximum  range.  The  advan- 
tages of  the  angle  of  greatest  range  are :  1st.  Economy 
of  powder;  2d.  Diminished  recoil,  and  strain  on  the 
piece,  bed,  and  platform ;  3d.  More  uniform  ranges. 

When  the  distance  is  not  great,  and  the  object  is  to 
penetrate  the  roofs  of  magazines,  buildings,  <fcc.,  the 
force  of  fall  may  be  increased  by  firing  under  an  angle 
of  60°.  The  ranges  obtained  under  an  angle  of  60°  are 
about  one-tenth  less  than  those  obtained  with  an  angle 
of  45°. 

If  the  object  be  to  produce  effect  by  the  bursting  of 
the  projectile,  the  penetration  should  be  diminished  by 
firing  under  an  angle  of  30°. 

When  the  object  is  not  on  a  level  with  the  piece,  the 
angle  of  greatest  range  is  considered  in  practice  to  be 
45°+|-0,  or  45  —  ^-0,  0  being  the  angle  of  elevation  or 
depression  of  the  object.  Thus  to  attain  a  magazine, 
for  instance,  situated' on  a  hill,  for  which  0=15°,  the 
angle  of  greatest  range  is  52|-°  instead  of  45°. 

The  angle  of  fire  being  fixed  at  45°  for  objects  on  the 
same  level  with  the  piece,  the  range  is  varied  by  vary- 
ing the  charge  of  powder.  The  practical  rule  is  founded 
on  the  knowledge  of  the  amount  of  powder  necessary 
to  diminish  or  increase  the  range  10  yards.  For  the 
French  8   and   10  inch   siege-mortars,  this   amount  is 


444  LOADING   AND    POINTING    FIRE-ARMS. 

about  60  grains  for  the  former,  and  125  grains  for  the 
latter. 

A  practical  rule  for  finding  the  time  of  flight  by 
which  the  length  of  the  fuze  is  regulated,  is  to  take  the 
square  root  of  the  range  in  feet,  and  divide  it  by  four ; 
the  quotient  is  the  approximate  time  in  seconds. 

Stone-mortars  are  pointed  in  the  same  manner  as 
common  mortars :  the  angle  of  fire  for  stones  is  from 
60°  to  75°,  in  order  that  they  may  have  great  force  in 
falling;  the  angle  for  grenades  is  about  33°,  in  order 
that  their  bursting  effect  may  not  be  destroyed  by  their 
penetration  into  the  earth. 

440.  Nigut-flring.  Cannon  are  pointed  at  night  by 
means  of  certain  marks,  or  measurements,  on  the  car- 
riage and  platform,  which  are  accurately  determined 
during  the  day. 

In  the  case  of  guns  and  howitzers,  the  elevation 
may  be  determined  by  marking  the  elevating  screw 
where  it  enters  the  nut,  or  by  measuring  the  distance 
between  the  head  of  the  screw  and  stock.  In  the 
case  of  mortars,  the  position  of  the  quoin  may  be 
determined  by  marking,  or  by  nailing  a  cleat  on  the 
bolster. 

The  direction  of  a  carriage  or  mortar-bed  is  deter- 
mined by  nailing  strips  of  boards  along  the  platform, 
as  guides  to  the  trail  and  wheels;  to  prevent  the  strips 
from  being  injured  by  the  recoil,  they  should  be  nailed 
at  a  certain  distance  from  the  carriage,  or  bed,  and  the 
space  filled  up  with  a  stick  of  proper  width,  which 
should  be  removed  before  firing.  The  chassis  of  a  sea- 
coast  carriage  can  be  secured  in  a  particular  direction 
by  firmly  chocking  the  traverse  wheels. 


GRADUATION    OF   REAR-SIGHTS.  445 

440.  Pointing  smaii-anns.  The  rear-sights  of  small- 
arms  are  graduated  with  elevation  marks  for  certain 
distances,  generally  every  hundred  yards;  in  aiming 
with  these,  as  with  all  other  arms,  it  is  first  necessary  to 
know  the  distance  of  the  object.  This  being  known, 
and  the  slider  being  placed  opposite  the  mark  corre- 
sponding to  this  distance,  the  bottom  of  the  rear-sight 
notch,  and  the  top  of  the  front  sight,  are  brought  into  a 
line  joining  the  object  and  the  eye  of  the  marksman. 
The  term  coarse-sight  is  used  when  a  considerable  por- 
tion of  the  front-sight  is  seen  above  the  bottom  of  the 
rear-sight  notch;  and  the  term  fine-sight,  when  but  a 
small  portion  of  it  is  seen.  The  graduation  marks  being 
determined  for  a  fine-sight,  the  effect  of  a  coarse-sight  is 
to  increase  the  true  range  of  the  projectile. 

441.  Graduation  of  rear-sigh t§.  If  the  form  of  the 
trajectory  be  known,  the  rear-sight  of  a  fire-arm  can  be 
graduated  by  calculation;  the  more  accurate  and  reli- 
able method,  however,  is  by  trial.  Suppose  it  be  re- 
quired to  mark  the  graduation  for  100  yards;  the  slider 
is  placed  as  near  the  position  of  the  required  mark  as 
the  judgment  of  the  experimenter  may  indicate ;  and, 
with  this  elevation,  the  piece  is  carefully  aimed,  and 
fired,  say  ten  times,  at  a  target  placed  on  level  ground, 
at  a  distance  of  100  yards.  If  the  assumed  position  of 
the  slider  be  correct,  the  centre  of  impact  of  the  ten 
shot-holes  will  coincide  with  the  point  aimed  at ;  if  it 
be  incorrect,  or  the  centre  of  impact  be  found  below 
the  point  aimed  at,  then  the  position  of  the  slider  is  too 
low  on  the  scale.  Let  P  be  the  point  aimed  at,  and  P* 
the  centre  of  impact  of  the  cluster  of  shot-holes;  we 
have,  from  close  similarity  of  the  triangles,  A!F :  FP:: 


446  LOADING   AND    POINTING    ITRE-AKMS. 


Fig.  144 

A' A" :  PP\  from  which  we  can  determine  A'Ar\  the 
quantity  that  must  be  added  to  AA',  to  give  the  cor- 
rect position  of  the  graduation  mark  for  100  yards.  If 
the  centre  of  impact  had  been  above  i3,  the  trial  mark 
would  have  been  too  high.  Lay  off  the  distance  A  A" 
above  A",  on  the  scale,  and  we  obtain  an  approximate 
graduation  for  200  yards,  which  should  be  corrected  in 
the  same  way  as  the  preceding,  and  so  on.  The  dis- 
tance PP'  is  found  by  taking  the  algebraic  sum  of  the 
distances  of  all  the  shots  from  the  point  P,  and  dividing 
it  by  the  number  of  shots.  It  will  be  readily  seen  that 
an  approximate  form  of  the  trajectory  may  be  obtained 
by  drawing  a  series  of  lines  through  the  different  grad- 
uation marks  of  the  rear- sight,  and  the  top  of  the  front- 
sight,  and  laying  off  from  the  front-sight,  on  each  line, 
the  corresponding  range.  The  points  thus  determined 
are  situated  in  the  required  trajectory. 

442.  Distance  of  object.  Various  instruments  have 
been  devised  to  determine  the  distances  of  objects,  based 
on  the  measurement  of  the  visual  angles  subtended  by 
a  foot  or  cavalry  soldier,  of  mean  height,  at  different 
distances ;  but  these  instruments  are  considered  of  little 
practical  value,  especially  in  the  excitement  of  action. 
Every  officer  and  soldier  should  be  taught  to  estimate 
distances  by  the  eye,  and  in  so  doing  much  assistance  is 
derived  from  knowing  what  parts  of  a  soldier's  dress,  or 
equipments,  are  visible  at  certain  distances.  These  data 
vary  with  the  power  of  the  eye,  and  each  soldier  should 


TABLES    OF    FIRE.  447 

be  required,  by  comparison  and  reflection,  to  create  a 
standard  for  his  own. 

In  firing  cannon,  the  point  at  which  the  projectile 
strikes  the  ground  or  bursts,  can  generally  be  observed, 
and  from  it,  the  error  of  aim  can  be  corrected  in  a  few 
fires ;  this,  however,  does  not  hold  true  for  small-arm 
projectiles,  which  are  seldom  seen  to  strike  the  ground, 
unless  the  soil  be  dusty. 

In  the  defence  of  sea-coast  batteries,  the  distances  of 
objects  may  be  determined  by  their  proximity  to  known 
objects,  as  fixed  buoys,  or  by  their  bearing  with  refer- 
ence to  prominent  landmarks.  Plane-tables  may  be 
also  used  to  determine  the  distances  of  objects. 

The  degree  of  accuracy  with  which  the  distance  of 
an  object  should  be  known,  depends  somewhat  on  the 
size  of  the  object  and  the  inclination  of  the  trajectory  to 
the  line  of  sight ;  if  the  object  be  large  and  the  trajec- 
tory vary  but  slightly  from  the  line  of  sight,  it  is  not 
necessary  to  know  the  exact  distance,  provided  the  aim 
be  accurately  taken. 

TABLES  OF  FIKE. 

443.  Purpose.  The  nature  and  purpose  of  a  table 
of  fire  should  be  explained  in  connection  with  the  sub- 
ject of  pointing  cannon.  A  properly  constructed  table 
of  fire,  for  a  particular  piece,  contains  the  range  and 
time  of  flight  for  each  elevation,  charge  of  powder,  and 
kind  of  projectile.  Its  purpose  is  to  assist  the  artillerist 
in  attaining  his  object  without  waste  of  time  and  am- 
munition, and  also  when  the  effect  of  shot  cannot  be 
seen  on  account  of  the  dust  and  smoke  of  the  battle- 


448 


LOADING    AND    POINTING    FIEE-AEMS. 


field.  The  first  few  shots  generally  produce  a  great 
effect  on  the  enemy,  and  it  is  very  important  that  they 
should  "be  directed  with  some  knowledge  of  their  results, 
which,  in  the  field,  can  only  be  attained  by  experience, 
or  from  the  data  afforded  by  a  table  of  fire. 

The  following  is  the  form  of  a  table  of  fire  for  guns 
and  howitzers : 


KIND   OF 
ORDNANCE. 

POWDER. 

PROJECTILE. 

ELEVATION. 

RANGE. 

TIME. 

Lbs. 

Lbs. 

0                ' 

Yards. 

Sec'ds. 

»f 

29,  (solid.) 

5°  0' 

2099 

7.5 

7°  0' 

2894 

9.1 

10°  0' 

3700 

11.6 

Armstrong  gun, 

12°  0' 

4196 

14.2 

4-inch  bore. 

15°  0' 

477G 

17.1 

20°  0' 

6070 

21.4 

25°  0' 

6580 

25. 

30°  0' 

7555 

31. 

35°  0' 

9000 

The  ranges  in  the  foregoing  table  were  determined 
at  West  Point,  in  1860,  and  are  the  mean  of  five  shots 
for  each  angle  of  elevation.  The  ranges  obtained  with 
the  best  American  muzzle-loading  rifle-cannon  compare 
favorably  with  these. 

Tables  of  fire,  for  the  different  service  cannon,  may 
be  found  in  the  Ordnance  and  Artillery  Manuals,  and 
the  XIII.  chapter  of  this  work. 


EAPIDITY  OF  FIKE. 

444.  Depends  on  size  of  piece,  dec.  The  rapidity  with 
which  cannon  can  be  loaded  and  discharged  depends 
on  the  size  of  the  piece,  the  construction  of  the  carriage, 
and  the  care  required  in  aiming. 


449 

Field-cannon.  Field-cannon  can  be  discharged  with 
careful  aim,  about  twice  per  minute ;  in  case  of  emer- 
gency, when  closely  pressed  by  the  enemy,  canister-shot 
may  be  discharged  four  times  per  minute.  The  12-pdr. 
boat-howitzer  of  the  navy,  with  experienced  gunners, 
can  be  discharged  at  the  rate  of  sixteen  times  per  minute. 

Siege-cannon.  Siege-guns  are  generally  discharged 
about  twelve  times  per  hour ;  if  necessary,  they  can  be 
discharged  as  rapidly  as  twenty  times  per  hour.  Iron 
cannon  can  be  fired  more  rapidly  than  bronze,  as  the 
latter  metal  is  softened  by  the  heat,  and  the  piece  is 
liable  to  bend.  Siege-mortars  can  be  conveniently  fired 
twelve  times  per  hour,  and  more  rapidly  than  this  if 
the  object  be  large,  as  a  city.  Siege-howitzers  can  be 
fired  about  eight  times  in  an  hour. 

Sea-coast  cannon.  The  fire  of  a  sea-coast  cannon  de- 
pends much  on  the  ease  with  which  its  carriage  can  be 
manoeuvred.  The  heaviest,  or  15-in.  gun,  mounted  on 
the  new  iron  carriage,  can  be  loaded  and  fired  in  V  10v; 
the  time  required  in  aiming  depends  on  the  angle 
through  which  the  chassis  is  to  be  traversed,  and  piece 
elevated,  or  depressed ;  it  can  be  traversed  through  an 
angle  of  90°  in  2'  20". 

Small-arms.  Muzzle-loading  small-arms  can  be  dis- 
charged two  or  three  times  in  a  minute,  and  breech-load- 
ing arms  about  ten  times;  the  revolver  can  be  dis- 
charged much  more  rapidly  for  six  shots. 

This  quality  of  a  military  fire-arm  should  be  carefully 
guarded,  as  it  is  found  that  soldiers  are  prone  to  dis- 
charge their  pieces  in  the  excitement  of  battle  without 
taking  proper  aim,  and  ■  consequently  to  waste  their 

ammunition. 

29 


450  DIFFERENT   KINDS    OF   FIEES. 


CHAPTER  X. 
DIFFERENT  KINDS  OF  FIRES. 

445.  cia§§iflcation.  Artillery  fires  are  distinguished 
by  the  manner  in  which  the  projectile  strikes  the  ob- 
ject— as  direct,  ricochet,  rolling,  and  plunging  fires  ;  by 
the  nature  of  the  projectile,  as  solid  shot,  shell,  shrapnel, 
grape,  and  canister  fires;  and  by  the  angle  of  ele- 
vation, as  horizontal  fire,  or  the  fire  of  guns  and  how- 
itzers under  low  angles  of  elevation,  and  vertical  fires, 
or  the  fire  of  mortars,  under  high  angles  of  elevation. 

446.  Direct  nre.  A  fire  is  said  to  be  direct  when 
the  projectile  hits  its  object  before  striking  any  inter- 
mediate object,  as  the  surface  of  the  ground,  or  water. 
This  species  of  fire  is  employed  where  great  penetration 
is  required,  as  the  force  of  the  projectile  is  not  dimin- 
ished by  previous  impact ;  it  is  necessarily  employed 
for  spherical-case  shot,  and  for  rifle-cannon  projectiles, 
which,  from  their  form,  are  liable  to  be  deflected,  by 
previously  striking  a  resisting  substance  ;  it  is  also  used 
for  all  field-cannon  projectiles,  when  the  nature  of  the 
ground  does  not  insure  a  regular  rebound. 

To  point  apiece  in  direct  fire,  bring  the  line  of  sight 
to  bear  upon  the  object,  and  then  elevate  the  piece  accord- 
ing  to  the  distance. 

447.  Ricochet  fire.  When  a  projectile  strikes  the 
ground,  or  water,  under  a  small  angle  of  fall,  it  pene- 
trates obliquely  to  a  certain  distance,  and  is  then  re- 


RICOCHET   FIRE.  451 

fleeted  at  an  angle  greater  than  the  angle  of  fall ;  the 
reason   for  this   is,  that   the  projectile,  in  forming  the 

furrow,  loses  a  portion  of  its 
velocity,  making  the  distance 
from  A  (fig.  145),  the  point  at 
Fig.  145.  '   which  it  enters  the  ground,  to 

O,  or  the  vertical  drawn  through  the  deepest  point, 
greater  than  the  distance  from  C  to  D,  the  point  where 
it  leaves  the  ground. 

As  this  recurs  every  time  the  projectile  strikes  the 
ground,  it  follows  that  the  trajectory  is  made  up  of  a 
series  of  rebounds,  or  ricochets,  each  one  shorter  and 
more  curved  than  the  preceding  one. 

The  number,  shaj)e,  and  extent  of  the  ricochets,  de- 
pend on  the  nature  of  the  surface  struck,  the  initial 
velocity,  shape,  size,  and  density  of  the  projectile,  and 
on  the  angle  of  fall. 

A  spherical  projectile  ricochets  well  on  smooth  water, 
when  the  angle  of  fall  is  less  than  8°,  but  if  the  surface 
of  the  water  be  rough,  very  little  dependence  can  be 
placed  on  the  extent  of  the  ricochet.  Captain  Dahlgren 
cites  a  case  as  coming  under  his  observation  where  the 
distance  between  the  first  and  second  rebound  was  in- 
creased from  400  to  800  yards  by  a  strong  wind ;  at 
the  same  time,  the  height  of  the  highest  point  of  the 
curve  was  increased  from  a  very  small  distance  above 
the  water,  to  more  than  50  feet,  which  would  have  ren- 
dered it  ineffective  against  the  hull  of  a  ship.  From 
the  same  causes  the  lateral  deviations  in  ricochet  fire 
will  be  very  considerable,  amounting,  in  some  cases,  to 
between  100  and  200  yards  in  the  entire  range. 

In  general,  those  projectiles  which  present  a  uniform 


452  DIFFERENT    KINDS    OF   FIRES. 

surface,  and  have  the  least  penetrating  power,  are  most 
suitable  for  ricochet  firing ;  hence,  large  shells  fired  with 
small  charges  are  more  suitable  than  solid  shot,  and 
round  projectiles  more  suitable  than  those  of  an  oblong 
form.  The  distance  at  which  the  larger  size  shells  will 
ricochet  on  water  is  about  3,000  yards,  the  axis  of  the 
piece  being  horizontal  and  near  the  water. 

Where  used,  &c.     Ricochet  fire  is  employed  in  siege 
operations  to  attain  the  face  of  a  work  in  flank,  or  in 


Fig.  146. 

reverse  (see  fig.  146),  and  on  the  field,  or  on  water, 
when  the  object  i3  large  and  its  distance  is  not  accu- 
rately known. 

The  character  of  ricochet  fire  i3  determined  by  the 
angle  of  fall,  or  the  angle  included  between  the  tan- 
gent of  the  trajectory  and  horizon  at  the  point  of  fall* 
There  are  two  kinds  of  ricochet  fire — the  flattened,  in 
which  the  angle  of  foil  is  between  2°  and  4° ;  and  the 
curvetted,  in  which  the  angle  of  fall  is  between  6° 
and  15°. 

The  principal  pieces  employed  in  ricochet  fire  in 
siege  operations  are  the  8-inch  howitzer,  and  the  8  and 
10-inch  common  mortars;  the  first  two  may  be  used 
when  the  angle  of  fall  is  less  than  10°,  and  the  10-inch 
mortar  when  the  angle  of  fall  is  less  than  15° — the 
proper  elevation  being  given  to  the  mortar  by  raising 
the  rear  portion  of  the  bed.     With  these  pieces,  the 


PEACTICAL    EULES    FOE    EICOCHET   FIEE.  453 

limit  of  ricochet  is  about  600  yards.  Solid  shot  should 
not  be  used  in  ricochet  fire  for  any  distance  less  than 
200  yards,  as  it  would  then  be  necessary  to  diminish 
its  velocity  so  much  as  to  destroy  its  percussive  effect. 
In  ricochet  firing  against  troops  in  the  open  field,  the 
'O  r^ingle  of  fall  should  not  exceed  3°. 

7/  448.  Practical  rules  for  ricochet  Are.  In  enfilading 
^^*The  face  of  a  work,  the  form  of  the  trajectory  and  point 
of  fall  should  be  such  that  the  projectile  will  strike  the 
surface  of  the  terreplein  the  greatest  number  of  times ; 
the  object  being  to  destroy  the  men,  carriages,  and 
traverses  situated  upon  it.  To  do  this,  the  projectile 
should  be  made  to  graze  the  crest  of  the  adjacent 
parapet,  and  strike  the  terreplein  as  near  the  foot  of 
the  interior  slope  as  possible ;  the  distance  of  the  crest, 
and  its  height  above  the  terreplein  and  battery,  should 
therefore  be  known. 

The  formulas  in  chapter  VIII.  furnish  accurate  means 
for  calculating  the  various  elements  of  ricochet  fire,  but 
they  are  too  complicated  for  use  in  the  field ;  it  is  there- 
fore proposed  to  deduce  simple  and  practical  rules  for 
this  purpose. 

1st.  To  find  the  angle  of  arrival.  The  angle  of  arri- 
val is  the  angle  which  the  tangent  to  the  trajectory  at 
the  crest  of  the  parapet  makes  with  the  horizon.     Let 

A  be  the  crest,  and  B  the 
point  of  fall  (fig.  147); 
the  distance  A  B  being 
short,  the  portion  of  the 
trajectory  included  be- 
tween these  two  points 
may  be  considered  a  right  line,  and  the  angle  of  fall 


454  DIFFEKENT   KINDS    OF   FIEES. 

and  arrival  will  be  equal.  Calling  a  the  angle  of  fall, 
and  erecting  the  perpendicular  B  (7,  we  have, 

BO 
a  =ACT 
or,  the  tangent  of  the  angle  of  arrival  is  equal  to  the  ver- 
tical distance  of  the  point  of  fall  below  the  crest,  divided 
by  the  horizontal  distance. 

Within  the  limits  of  ricochet  fire,  the  angles  may  be 
supposed  proportional  to  their  tangents;  calling  the 
tangent  of  6°  (which  is  0.1051)  0.1,  we  have  the  follow- 
ing proportion : 

*:6.::Jg:0.1, 

or, 

0=60°^, 
AC 

or,  the  angle  of  arrival  is  equal  to  60°  multiplied  by  the 
ratio  of  the  horizontal  and  vertical  distances  of  the  point 
of  fall  from  the  crest  of  the  parapet. 

This  rule  gives  the  angle  of  arrival  without  the  aid 
of  a  table  of  natural  tangents. 

2d.  To  find  the  angle  of  fire.  The  distance  of  the 
parapet  is  always  known,  and  the  angle  of  elevation  of 
the  crest  can  be  determined  by  sighting  along  the  long 
branch  of  a  gunner's  quadrant,  and  observing  the  posi- 
tion of  the  plummet  on  the  arc. 

In  consequence  of  the  nearness  of  the  object,  and  the 
large  size  and  low  initial  velocity  of  the  projectile,  the 
resistance  of  the  air  in  this  species  of  ricochet  iire  may 
be  neglected,  which  makes  the  trajectory  a  parabola.  In 
this  case  the  angle  of  fall  is  equal  to  the  angle  of  fire, 
when  the  object  is  situated  in  the  same  horizontal  plane 


PRACTICAL    RULES    FOR    RICOCHET    FIRE.  455 

with  the  piece ;  if  it  be  not  in  the  same  horizontal  plane, 
let  BAM  (fig.  148),  which  is  the  angle  of  elevation 


Fig.  148. 

of  the  crest,  be  represented  by  e.  As  the  angle  e  is 
very  small,  we  are  at  liberty  to  suppose  C  A  B=A  B  C. 
Through  the  point  B  draw  the  horizontal  line  B  I),  the 
angle  C  B  D  is  equal  to  the  angle  of  arrival  a;  the 
lines  B  D  and  A  M  being  parallel,  the  angle  A  B  D=e ; 
therefore  C  A  B  —  C  B  A=a+e,  but  the  angle  C  A  M 
=  0  A  B-\-e=a-{-2e :  or,  the  angle  of  fire  is  equal  to  the 
angle  of  arrival  increased  by  twice  the  angle  of  elevation 
of  the  crest  of  the  parapet. 

From  the  erroneous  suppositions  made  in  the  course 
of  the  preceding  demonstrations,  it  will  be  seen  that 
the  rules  deduced  should  give  too  great  an  angle  of  fire. 
In  practice,  this  angle  should  be  somewhat  greater  than 
the  true  angle,  in  consequence  of  the  deviations,  which 
render  the  projectile  liable  to  strike  against  the  parapet, 
and,  of  course,  destroy  its  effect. 

3d.  To  find  the  charge.  When  a  projectile  moves  in 
vacuo,  we  have  seen  that  the  distance  which  it  falls 
below  the  line  of  fire,  in  the  time  t,  is  \  gt2 ;  and  for  a 
given  distance,  t  is  inversely  proportional  to  the  initial 
velocity  V;  hence  the  distances  which  the  same  pro- 
jectile, fired  with  different  velocities,  would  fall  below 
the  line  of  fire,  in  the  distance  A  O  (fig.  149),  will  be 
inversely  proportional  to  the  squares  of  the  initial  veloci- 


456 


DIFFERENT    KINDS    OF    FIKES. 


Fig.  149. 

If  we  suppose  the  lines  of  fire  of  two  projectiles  be 
A  C  and  A  C,  and  the  initial  velocities,  V  and  V\  to 
be  such  that  they  will  fall  the  distances  B  O  and  B'  Q\ 
and  that  the  angles  subtended  by  these  lines  be  propor- 
tional to  the  lines  themselves,  we  shall  have 
BAO.BAC'::  V'2 :   V2 

It  has  been  seen  that  the  initial  velocities  of  small 
charges  are  nearly  proportional  to  the  square  roots  of 
the  weight  of  the  charges.  Calling  the  corresponding 
charges  (7  and  (?,  we  have 

B  AC   :  B'  A  C  : :  C:  C, 
or,  for  the  same  distance  of  the  object,  the  chaises  should 
be   inversely  proportional  to  the  difference  between  the 
angle  of  fire  and  angle  of  elevation  of  the  object. 

Take  the  case  in  which  the  objects  are  situated  at 
different  distances,  as  B  and  B"  (jig.  149),  but  have  the 
same  angle  of  elevation  e  /  and  suppose  we  wish  to 
strike  them  with  the  same  angle  of  fire ;  what  should  be 
the  relation  between  the  charges  % 

Substitute  in  the  expression  \gtf,  the  value  of  t,  which 

is  —,  in  which  D  is  the  distance,  and  V  the  initial  ve- 

locity  of  the  projectile,  we  have  \g  — -^  which  shows 

that  the  distance  which  a  projectile  falls  below  the  line 
of  fire  is  directly  proportional  to  the  square  of  the  dis- 
tance measured  on  the  line  of  fire,  and  inversely  pro- 


PRACTICAL   RULES    FOR    RICOCHET   FIRE.  457 

portional  to  the  square  of  the  velocity.  But  the  dis- 
tances B "  C"  and  B  C  are  proportional  to  A  0"  and 
A  C,  or  B"  and  B,  and,  recollecting  that  the  squares  of 
the  initial  velocities  are  proportional  to  the  charges 
(7  and  C",  we  have 

TV2  7)2 

B" -  B-  •—  •  — 

-  c»'  c 

or, 

&":Z>i:  C"  :  C, 

or,  for  the  same  difference  between  the  angle  of  fire  and 
the  angle  of  elevation  of  the  object,  the  charges  are  pro- 
portional to  the  distances. 

In  arriving  at  the  foregoing  rules,  we  have  committed 
three  errors:  1st.  Supposing  the  sides  of  the  triangles 
proportional  to  the  angles.  2d.  Considering  the  re- 
sistance of  the  air  nothing;  and,  3d.  That  the  initial 
velocities  are  proportional  to  the  square  roots  of  the 
charges.  The  errors  resulting  from  these  suppositions 
are  not  only  small  in  themselves,  but  the  2d  and  3d 
are  of  a  nature  to  counteract  each  other. 

By  means  of  the  foregoing  relations  suitable  charges 
can  be  calculated  for  every  case  of  practice,  when  we 
know  the  charge  corresponding  to  a  given  distance,  and 
to  a  given  difference  between  the  angle  of  fire  and  the 
angle  of  elevation  of  the  object.  Represent  by  C  the 
charge  corresponding  to  a  distance,  B\  and  to  a  differ- 
ence, JE\  between  the  angle  of  fire  and  the  angle  of  ele- 
vation of  the  object;  we  have  the  charge,  (7,  corre- 
sponding to  the  distance,  B,  and  the  difference,  BJ,  be- 
tween the  two  angles,  by  means  of  the  formula 

C~DxC'E' 


458  DIFFEKENT   KINDS    OF   FIRES. 

The  factor,  is  a  constant  number  for  each  cali- 
bre. This  number  may  be  considered  as  the  charge 
corresponding  to  the  distance  of  1  yard,  and  to  a  differ- 
ence of  1°  between  the  angle  of  fire  and  of  elevation  of 
the  object. 

For  the  French  8-inch  siege  howitzer,  the  value  of 
this  factor  has  been  found  by  careful  experiment  to  be 
0.31  oz.  Making  an  allowance  for  difference  of  weight 
of  projectile  and  unit  of  distance,  it  becomes  0.28  oz. 
for  the  American  8-inch  siege  howitzer. 

Example. — Find  the  angle  of  arrival,  angle  of  fire,  and  charge  of 
powder,  necessary  to  hit,  with  an  8-inch  howitzer  shell,  a  point  on  a 
terreplein,  12  yards  behind  a  traverse  which  is  2.5  yards  high  and  350 
yards  from  the  battery — the  angle  of  elevation  of  the  crest  being  1°, 
and  the  command  6  yards. 

For  the  angle  of  arrival  we  have 

B  C    60°  x  2.5 

^60^==-T2-=12°30'- 

For  the  angle  of  fire  we  have 

0==a  +  2f=12°  30-f2°==14o  30'. 
For  the  charge  we  have 

„     D  350. 

tf=^0.28oz.  ==—-0.28  =  7.25  oz. 

Hj  »  lo.O 

449.  Roiling  fire.  Rolling  fire  is  a  particular  case  of 
ricochet  fire,  produced  by  placing  the  axis  of  the  piece 
parallel,  or  nearly  so,  with  the  ground.  It  is  generally 
used  in  field  service.  When  the  ground  is  favorable  for 
ricochet,  the  projectile,  in  rolling  fire,  has  a  very  long 
range,  and  never  passes  at  a  greater  distance  above  the 
ground  than  the  muzzle  of  the  piece;  it  is  therefore 
more  effective  than  direct  fire,  as  may  be  seen  by  in- 
specting ^g.  150. 


EFFECT  OF  FIRE  IN   GENERAL.  459 


Fig.  150. 

To  point  a  piece  in  rolling  fire,  direct  it  at  the  object, 
and  depress  the  natural  line  of  sight  so  as  to  pierce  the 
surface  of  the  ground  about  80  yards  in  front  of  the 
muzzle;  if  the  piece  be  sighted  for  the  pendulum 
hausse,  aim  directly  at  the  object  with  the  lowest  line  of 
sight,  or  with  the  slider  fixed  at  the  zero  point  of  the 
scale. 

450.  Plunging  fire.  A  fire  is  said  to  be  plunging  when 
the  object  is  situated  below  the  piece.  This  iire  is  par- 
ticularly effective  against  the  decks  of  vessels. 

451.  Effect  of  fire  in  general.  Before  proceeding  to 
describe  the  fires  of  different  kinds  of  projectiles,  it  may 
be  proper  to  explain  what  is  meant  by  accuracy  of  fire, 
and  to  determine  a  suitable  measure  for  it.  It  has  been 
seen  that  there  are  causes  constantly  at  work  to  deviate 
nearly  every  projectile  from  its  true  path.  As  the  effect 
of  these  deviating  forces  cannot  be  accurately  foretold, 
there  is  only  a  probability  that  the  projectile  will  strike 
the  object  against  which  the  piece  is  pointed.  The  de- 
gree of  probability  is  called  accuracy  of  fire. 

For  all  projectiles  of  the  same  nature,  the  chance  of 
hitting  an  object  increases  with  the  velocity  and  weight 
of  the  projectile,  whereby  the  effects  of  the  deviating 
forces  are  diminished ;  it  also  increases  as  the  size  of  the 
object  is  equal  to,  or  greater  than,  the  mean  deviations, 
and  as  the  trajectory  more  nearly  coincides  with  the  line 
of  sight.  If  the  size  of  the  object  be  greater  than  the 
extreme  deviation,  and  the  trajectory  coincide  with  the 


460 


DIFFERENT    KINDS    OF    FIRES. 


line  of  sight,  the  projectile  will  be  certain  to  hit  the 
object  at  all  distances. 

452.  Measure  of  deviation.  For  the  same  trajectory, 
therefore,  the  mean  deviation  of  a  projectile  at  a  given 
distance  may  be  taken  as  an  indirect  measure  of  its  ac- 
curacy at  this  distance. 

To  obtain  this  mean  deviation,  let  the  piece  be 
pointed  at  the  centre  of  a  target,  stationed  at  the  re- 
quired distance,  and  fired  a  certain  number  of  times — 
say  ten — and  let  the  positions  of  the  shot-holes,  meas- 
ured in  vertical  and  horizontal  directions,  be  arranged 
in  the  following  tabular  form : 


o 

i 

1 

Distances  from  centre  of  target,  in  feet. 

Distances  from  centre  of  impact,  in  feet 

Vertical. 

Horizontal. 

Vertical. 

Horizontal. 

Above. 

Below. 

Eight. 

Left. 

Above.    1    Below. 

Eight 

Left. 

1 

2 
3 

3 

6 

1 

4 

2 

2 

4.33   ' 

4.66 

.33   j 

2.66 
.66 

3.33 

3 

1 

6 

2 

4.66 

4.66 

3.33 

3  33 

4-^3  =  1.33 

4-^3  =  1.33 

9.32  -^  3  =  3.1116.66  -4-8=  2.22 

The  algebraic  sum  of  the  distances  in  each  direction, 
divided  by  the  number  of  shots,  gives  the  position  of 
the  centre  of  impact  in  this  direction.  In  the  above 
table  the  position  of  the  centre  of  impact  is  found  to  be 
1.33  ft.  below,  and  1.33  ft.  to  the  right,  of  the  centre 
of  the  target.  To  obtain  the  mean  deviation,  it  is 
necessary  to  refer  each  shot-hole  to  the  centre  of  impact 
as  a  new  origin  of  co-ordinates ;  and  this  is  done  by 
subtracting  the  tabular  distance  from  the  distance  of 
the  centre  of  impact,  if  both  be  on  the  same  side  of  the 


DEVIATIONS.  461 

centre  of  the  target,  and  adding  them,  if  on  different 
sides.  The  sum  of  all  the  distances  thus  obtained  in 
one  direction,  divided  by  the  number  of  shots,  gives 
the  mean  deviation  in  that  direction ;  which  in  the 
present  case  is  3.11  ft.  vertically,  and  2.22  horizontally. 
The  foregoing  affords  a  measure  for  the  accuracy  of 
fire  of  the  piece  and  projectile,  but  it  does  not  afford  a 
measure  for  marksmanship,  the  object  of  which  is  to  di- 
rect a  projectile  so  as  to  strike  a  given  point  or  surface. 
In  target-practice  with  sporting  rifles,  the  string,  or  sum 
of  the  distances  of  a  certain  number  of  shots,  from  the 
point  aimed  at,  is  taken  as  the  measure  of  accuracy. 
In  military  arms,  marksmanship  is  measured  by  the 
greatest  number  of  projectiles  out  of  a  certain  number, 
placed  in  a  target  of  given  size,  or  placed  within  a 
given  space  surrounding  the  centre  of  the  target. 

453.  Targets.  Targets  for  heavy  cannon  are  made 
of  cotton  cloth  (or  light  boards)  stretched  over  two 
upright  poles  firmly  secured  in  the  ground.  The  size 
varies  with  the  distance  :  for  1,000  yards  and  upward, 
it  should  be  about  20  feet  high  and  40  feet  long. 
Targets  for  the  field  service  are  made  of  the  same 
materials,  about  8  feet  high,  and  from  30  to  40  feet 
long.  Targets  for  small  arms,  if  permanent,  are  made 
of  cast-iron ;  if  portable,  of  a  wrought-iron  frame  cov- 
ered with  cotton  cloth.  For  distances  less  than  200 
yards,  they  should  be  6  feet  high  and  22  inches  broad; 
beyond  this  distance,  the  breadth  of  a  target  may  be 
increased  by  placing  two  or  more  of  these  targets  side 
by  side. 

454.  Deviations.  The  vertical  deviation  of  a  pro- 
jectile is  generally  greater  than  its  corresponding  hori- 


462  DIFFERENT    KINDS    OF    FIRES. 

zpntal  deviation,  and  this  difference  increases  with  the 
range.  As  objects  against  which  military  projectiles 
are  directed,  present  a  greater  extent  of  surface  in  a 
horizontal  than  in  a  vertical  direction,  it  "becomes  ne- 
cessary to  exercise  great  care  in  the  selection  of  the 
proper  angle  of  fire.  If  the  ground  or  water  in  front 
of  the  object  be  favorable  to  ricochet,  the  difficulty 
will  be  diminished  by  aiming  so  that  the  projectile 
will  strike  the  object  after  one  or  more  rebounds. 

455.  Solid-shot  firing.  Solid  shot  are  generally  used 
for  percussion  and  penetration,  and,  when  heated  to  a 
red  heat,  for  the  purpose  of  setting  fire  to  wooden 
vessels  or  buildings.  From  their  great  strength,  they 
can  be  fired  with  a  large  charge  of  powder,  which 
gives  them  great  initial  velocity,  and  having  great 
density,  which  diminishes  the  effect  of  the  resistance 
of  the  air,  they  have  great  range  and  accuracy.  In 
firing  hot  shot,  the  charge  should  be  reduced,  to  pre- 
vent too  great  penetration,  which  would  exclude  the 
air  and  render  combustion  impossible. 

The  extreme  range  of  field  artillery  is  about  3,000 
yards;  it  is  not  very  effective,  however,  beyond  1,700 
yards  for  the  6-pdr.,  and  2,100  yards  for  the  12-pdr. 
At  600  yards  the  horizontal  deviation  of  the  12-pdr. 
is  about  3  feet,  and  at  1,200  yards  it  is  about  12  feet. 
For  the  6-pdr.  the  deviations  are  somewhat  greater  at 
both  distances. 

The  service  of  solid  shot  demands  less  skill  than 
that  of  shells  and  spherical  case-shot,  and  they  are 
often  effective  when  the  latter  are  rendered  non-effect- 
ive by  untimely  explosion. 

456.  Shell-firing.     The  diameter  and  velocity  of  two 


SHELL-FIRING.  463 

projectiles  being  the  same,  the  retarding  effect  of  the 
air  is  inversely  proportional  to  their  weight  (see  page 
406)  ;  hence  a  shell  has  less  accuracy  and  range  than  a 
solid  shot  of  the  same  size,  in  the  proportion  of  3  to 
2 — these  numbers  representing  the  weights  of  a  solid 
shot  and  shell,  respectively. 

Field  s/iells.  As  shells  act  both  by  percussion  and 
explosion,  they  are  particularly  effective  against  ani- 
mate objects,  earthworks,  buildings,  block-houses  and 
shipping,  posts  and  villages  occupied  by  troops,  and 
against  troops  sheltered  by  accidents  of  the  ground; 
but  against  good  masonry  they  have  but  little  effect, 
as  they  break  on  striking.  Against  troops,  especially 
cavalry,  they  possess  a  certain  moral  effect  which  solid 
shot  do  not  possess.  They  are  used  to  form  breaches 
in  intrenchments,  in  which  case  they  act  as  small 
mines.  The  32-pdr.  shell  is  the  most  effective  field 
projectile  for  this  purpose;  and,  when  fired  with  a 
large  charge,  has  a  penetration  of  from  5  to  8  feet  in 
fresh  earth. 

The  extreme  range  of  field  shells  is  from  2,500  to 
3,000  yards.  The  24  and  32-pdr.  shells  burst  into 
about  eighteen  effective  fragments,  some  of  which  are 
thrown  to  a  distance  of  600  yards.  All  field  shells 
have  considerable  lateral  deviation;  it  is  stated  that 
the  24-pdr.  shell  is  sometimes  deviated  as  much  as  30 
yards  in  1,200. 

Mountain  shells.  The  extreme  range  of  the  moun- 
tain howitzer  is  about  1,200  yards,  after  three  or  four 
rebounds.  The  12-pdr.  shell  employed  in  this  service 
bursts  into  twelve  or  fifteen  fragments,  some  of  which 
are  thrown  to  a  distance  of  300  yards. 


464  DIFFERENT    KINDS    OF    FIRES. 

Siege  shells.  The  great  weight  of  an  8-inch  shell,  and 
the  large  quantity  of  powder  which  it  contains,  render 
it  a  very  formidable  projectile  against  the  traverses  and 
epaulements  of  siege  works. 

Sea-coast  shells.  In  sea-coast  defence,  the  8,  10,  and 
15-inch  shells  are  very  destructive  to  vessels  built  of  tim- 
ber. They  range  from  3  to  3|  miles;  but  the  angle 
which  the  trajectory  makes  with  the  line  of  sight  at  this 
distance  (about  40°)  renders  their  fire  very  uncertain 
against  individual  objects  of  the  size  of  a  ship ;  but  it  is 
presumed  that  they  would  have  the  effect  to  prevent  a 
blockading  fleet  from  lying  at  anchor  within  their  range, 
as  it  is  well  known  that  a  single  10-inch  shell,  striking 
on  the  deck  of  a  vessel,  has  sufficient  force  to  penetrate 
to  the  bottom  and  sink  her.  The  8-inch  shell  bursts 
into  28  or  30  fragments;  and  from  the  experiments 
made  at  Brest,  some  years  ago,  it  was  inferred  that  three 
of  four  of  these  shells,  properly  timed  and  directed, 
were  capable  of  disabling  a  ship  of  war. 

Mortar  shells  are  employed  to  break  through  the 
roofs  of  magazines,  <fec,  and  to  blow  them  up ;  to  de- 
stroy the  surface  of  the  terrepleins,  ditches,  <fcc,  by  form- 
ing deep  hollows,  which  are  produced  by  explosion,  and 
to  interrupt  the  communications  from  one  part  of  a  work 
to  another.  The  great  depth  to  which  mortar  shells 
penetrate  in  earth,  almost  entirely  destroys  the  effect 
of  their  fragments ;  some  remain  buried  in  the  ground, 
and  the  others  are  thrown  out  at  too  high  an  angle  to 
be  dangerous.  One  of  the  principal  objects  of  traverses, 
on  a  terreplein,  is  to  confine  the  bursting  effects  of  shells 
within  narrow  limits.  Mortar  shells  penetrate  from 
half  a  yard  to  one  yard  in  earth ;  and  the  amount  of 


SHRAPNEL  FIRING.  465 

earth  thrown  up  by  explosion  is  about  one  cubic  yard 
for  each  pound  of  the  bursting-charge.  Ordinarily,  the 
diameter  of  the  crater  at  the  top  is  two  or  three  times 
the  depth.  The  13-inch  shell  will  often  break  in  falling 
on  a  pavement*  Roofs  of  good  masonry,  little  more 
than  a  yard  thick,  are  sufficient  to  resist  the  penetration 
of  mortar  shells. 

The  effect  of  mortar-firing  is  generally  in  favor  of  the 
besiegers,  as  the  works  of  the  besieged  present  a  larger 
and  more  favorable  surface  for  the  action  of  shells. 
About  one-fifth  of  the  shells  fall  inside  of  a  demi-lune 
at  a  distance  of  650  yards,  and  about  one-third  at  a  dis- 
tance of  450  yards.  The  line  of  fire  should  be  taken  in 
the  direction  of  the  greatest  extent  of  the  part  to  be 
shelled.  The  fire  of  mortars  at  sea  is  veiy  uncertain, 
unless  the  object  be  very  large. 

Stone  mortars.  The  charge  of  a  stone  mortar  should 
be  small,  to  prevent  the  stones  and  grenades  from  being 
too  much  scattered.  A  charge  of  stones  is  generally 
scattered  over  a  space  varying  from  30  to  50  yards 
broad,  and  from  60  to  100  yards  long.  The  dispersion 
of  grenades  is  somewhat  less  than  this ;  the  larger  por- 
tion, however,  are  found  within  a  radius  of  12  or  15 
yards.  Each  grenade  furnishes  from  12  to  15  fragments 
in  a  radius  of  10  or  20  yards ;  some  of  the  fragments 
are  projected  to  a  distance  of  300  yards. 

45 7.  Shrapnel  firing.     When  a  shrapnel  or  case-shot 

bursts  in  its  flight,  the  fragments  of  the  case  and  the 

contained  jxrojectiles  are  influenced  by  two  forces,  viz., 

the  force  of  propulsion,  which  moves  each  piece  in  the 

direction  of  the  trajectory,   and  the  force  of  rupture, 

which  moves  it  in  the  direction  of  a  normal  to  the  sur- 
30 


466  DIFFERENT    KINDS    OF    FIRES. 

face  of  the  case.  The  path  described  by  each  fragment 
and  projectile  depends  on  the  angle  which  the  normal 
makes,  with  the  trajectory,  and  on  the  relative  velocities 


Fig.  151. 

generated  by  the  two  forces ;  and,  when  taken  together, 
these  paths  form  a  species  of  cone,  called  the  cone  of  dis- 
persion, the  apex  of  which  coincides  with  the  point  of 
rupture,  and  the  axis  is  the  trajectory,  prolonged.  Fig. 
151. 

The  velocity  of  a  projectile  diminishes  from  the  time 
it  leaves  its  piece,  while  the  velocity  generated  by  the 
rupturing  force  remains  constant.  It  follows,  therefore, 
that  the  dispersion  of  a  spherical  case-shot  increases  with 
the  distance,  while  the  force  of  impact  is  diminished. 

The  distance  at  which  a  spherical  case-shot  ceases  to 
be  effective  depends  on  the  relation  between  the  re- 
maining velocity  and  the  velocity  generated  by  the  force 
of  rupture.  The  improvements  which  have  lately  been 
introduced  into  this  species  of  projectile,  have  for  their 
objects,  to  increase  the  remaining  velocity  at  any  point 
by  increasing  the  propelling  charge,  and  to  diminish  the 
force  of  rupture,  and  at  the  same  time  increase  the  num- 
ber of  contained  projectiles  by  diminishing  the  burst- 
ing-charge. By  filling  the  interstices  of  the  bullets 
with  sulphur  or  rosin,  the  propelling  charge  of  a  spher- 
ical case-shot  can  be  made  the  same  as  that  of  a  solid 
shot.     (See  chapter  II.) 

It  is  considered  that  a  spherical  case-shot  is  effective 
when  a  large  portion  of  the  projectiles  have  sufficient 


SHRAPNEL  FIRING.  467 

force  to  penetrate  one  inch  of  soft  pine.  The  present 
12-pdr.  spherical  case-shot,  fired  with  a  charge  of  2^ 
pounds  of  powder,  has  a  remaining  velocity  of  about 
500  feet  at  a  distance  of  1,500  yards,  which  renders  it 
effective  at  this  distance. 

The  principal  difficulty  experienced  in  firing  a  spher- 
ical case-shot  is,  to  burst  it  at  the  proper  distance  in 
front  of  the  object.  This  arises  from  the  difficulty  of 
estimating  the  correct  distance  of  the  object,  the  rapid 
flight  of  the  projectile,  and  the  .difficulty  of  observing 
the  effect  of  a  shot  in  order  that  correction  may  be 
made  for  the  succeeding  one,  if  necessary.  To  overcome 
these  difficulties  requires  skill  and  judgment  on  the 
part  of  the  gunner,  and  great  accuracy  and  delicacy  in 
the  operation  of  the  fuze. 

The  proper  position  of  the  point  of  rupture  varies 
from  50  to  130  yards  in  front  of,  and  from  15  to  20  feet 
above,  the  object. 

The  mean  number  of  destructive  pieces  from  a  12-pdr. 
spherical  case-shot,  which  may  strike  a  target  9  feet 
high  and  54  feet  long,  situated  at  a  distance  of  800 
yards,  is  30. 

The  effect  of  spherical  case-shot  from  rifle-cannon  is 
said  to  extend  upward  of  2,000  yards.  This  arises 
from  the  fact  that  an  oblong  projectile  preserves  its  ve- 
locity for  a  much  longer  distance  than  a  round  one. 

The  weight  of  a  spherical  case-shot  is  about  the  same 
as  a  solid  shot  of  the  same  size,  and  being  fired  with  the 
same  charge  of  powder,  it  can  be  used  for  attaining 
long  ranges,  in  the  absence  of  solid  shot.  For  this 
purpose  the  fuze  should  not  be  cut. 

Spherical  case-shot  should  not  be  used  for  a  less  dis- 


468  DIFFERENT    KINDS    OF    FIRES. 

tance  than  500  yards ;  although  in  cases  of  emergency 
the  faze  may  be  cut  so  short  that  the  projectile  will 
burst  at  the  muzzle  of  the  piece,  in  which  case  it  will 
act  like  grape  or  canister  shot. 

458.  Grape  and  cani§ter  firing.  In  grape  and  canis- 
ter firing,  the  apex  of  the  cone  of  dispersion  is  situated 
in  the  muzzle  of  the  piece,  and  the  destructive  effect  is 
confined  to  short  distances.  The  shape  of  this  cone  is 
the  same  as  in  spherical  case-shot ;  its  intersection  by  a 
vertical  plane  is  circular,  while  that  of  a  horizontal 
plane,  as  the  ground,  is  an  oval,  with  its  greatest  diam- 
eter in  the  plane  of  fire.  The  greatest  number  of  pro- 
jectiles are  found  around  the  axis  of  the  cone,  while  the 
extreme  deviations  amount  to  nearly  one-tenth  of  the 
range. 

The  most  suitable  distance  for  field  canister-shot  is 
from  350  to  500  yards ;  if  the  ground  be  hard  and  the 
surface  be  uniform,  the  effect  may  extend  as  far  as  800 
yards.  In  cases  of  great  emergency  a  double  charge  of 
canister,  fired  with  a  single  cartridge,  may  be  used  for 
distances  between  150  and  200  yards. 

Under  favorable  circumstances,  one- third  of  the  whole 
number  of  contained  projectiles  will  strike  the  size  of  a 
half-battalion-front  of  infantry,  and  one-half,  the  front 
of  a  squadron  of  cavalry. 

Grape  and  canister  shot  are  employed  in  siege  and 
sea-coast  operations ;  in  the  latter,  they  are  effective 
against  boats,  and  the  rigging,  <fcc.,  of  vessels.  Grape- 
shot,  being  larger  than  canister-shot,  are  effective  at 
greater  distances. 

Canister-shot  for  the  mountain  service  are  not  effec- 
tive beyond  250  and  300  yards. 


SMALL-ARM  FIRING.  469 

459.  Small-arm  firing.  Beyond  200  yards,  the  fire 
of  the  smooth-bored  musket  becomes  very  uncertain 
against  individual  objects,  as  the  lateral  deviations 
often  exceed  four  feet ;  but  by  aiming  high  it  may  be 
made  effective  against  troops  in  mass  at  400  yards.  The 
fire  of  the  rifle-musket  is  effective  at  1,000  yards;  the 
angle  of  fall,  however,  is  so  great  (about  5°)  that  great 
care  must  be  exercised  in  determining  the  exact  dis- 
tance of  the  object.  If  the  ground  be  favorable,  the 
projectile  will  ricochet  at  1,000  yards,  wjiich  increases 
the  dangerous  space,  and  therefore  the  chances  of  hit- 
ting the  object.  The  limit  of  any  fire  is  determined  by 
the  distinctness  of  vision ; — the  limit  of  distinct  vision 
for  a  foot-soldier  is  about  1,100  yards ;  that  for  a  mount- 
ed soldier  is  about  1,300  yards. 

The  effect  of  small-arm  firing  depends  much  on  the 
skill  and  self-possession  of  the  soldier  in  action ;  for, 
without  these  qualities,  the  most  powerful  and  accurate 
arms  will  be  of  little  avail.  The  number  of  cartridges 
expended  for  each  person  disabled  in  previous  Europe- 
an wars  has  been  variously  stated  to  be  from  3,000  to 
10,000.  In  the  late  Mexican  war,  where  an  unusually 
large  proportion  of  the  American  troops  were  armed 
with  rifles,  this  number  has  been  estimated  to  be  from 
300  to  400. 

Where  a  soldier  discharges  his  piece  from  the  back 
of  a  horse,  as  in  the  cavalry  service,  the  effect  of  fire  is 
much  less  than  in  the  dragoon  and  mounted-rifle  ser- 
vices, where  he  rides  from  point  to  point,  but  discharges 
his  piece  on  foot. 

At  short  distances,  and  against  troops  in  mass,  two 
or  three  round  bullets  may  be  employed  with  effect ; 


470 


DIFFERENT   KINDS    OF    FIEES. 


the  bullets  should  be  so  small  that  they  will  readily 
drop  to  their  place  without  the  aid  of  the  ramrod. 
Buckshot  have  very  little  effect  beyond  100  yards. 

The  following  are  the  mean  deviations  of  the  rifle- 
musket  fired  from  a  shoulder  and  rest. 


DISTANCE. 

VERTICAL. 

HORIZONTAL. 

Yards. 

100 

600 

1000 

Inches. 

1.9 
22.2 
55.9 

Inches. 

1.5 
14.6 
25.5 

s 


^(i^d^; 


'^*~*VS 


EFFECT    ON    CAST-IKON.  471 


CHAPTER  XL 
EFFECTS  OF   PROJECTILES. 

460.  General  consi derations.  A  knowledge  of  the 
destructive  effects  of  projectiles  on  iron,  wood,  earth, 
and  masonry,  the  materials  of  which  covering  masses 
are  made,  is  of  very  great  importance  in  a  military  point 
of  view.  In  general,  these  effects,  and  particularly  that 
of  penetration,  depend  on  the  nature  of  the  projectile, 
its  initial  velocity,  and  the  distance  of  the  object. 

461.  Effect  on  cast-iron.  When  a  projectile,  animated 
with  a  great  velocity,  strikes  against  a  block  of  cast- 
iron,  it  is  partially  flattened,  and  at  the  same  time  it 
forms  a  rounded  indentation  in  the  surface  of  the  block, 
the  depth  of  which  increases  with  the  velocity  at  the 
moment  of  impact.  The  particles  composing  a  cone, 
the  base  of  which  is  the  surface  of  contact,  are  arrested 
by  the  impact;  the  remaining  particles  of  the  projectile, 
composing  a  ring  surrounding  this  cone,  move  on,  after 
impact,  by  their  inertia,  until  the  ring  breaks  into  pieces, 
which  fly  off  from  the  reflecting  surface.  The  ring  gen- 
erally breaks  into  five  pyramidal  pieces,  separated  by 
as  many  meridian  planes;  these  pieces  are  thrown  at 
various  distances,  depending  on  the  velocity  of  the  pro- 
jectile and  the  surface  of  impact. 

A  similar  effect  is  produced  upon  the  piece  struck ; 
that  is,  a  cone  of  particles,  having  for  its  base  the  surface 
of  contact,  is  set  in  motion,  which,  acting  like  a  wedge, 
tends  to  split  the  mass  into  five  pyramidal  pieces.     If 


472  EFFECTS    OF   PROJECTILES. 

the  velocity  of  the  projectile  be  not  sufficient  to  produce 
rupture,  cracks  will  be  generally  formed  in  the  direc- 
tions above  indicated. 

In  certain  experiments  made  in  France,  a  24-pdr.  shot, 
fired  with  a  charge  of  TV,  and  moving  with  a  velocity 
of  883  feet,  split,  in  two  shots,  to  the  depth  of  40  inches, 
a  block  of  cast-iron  12  inches  wide  by  40  inches  deep. 
The  fragments  of  the  block  and  shot  were  thrown  off 
with  sufficient  force  to  produce  the  most  destructive 
effect.  Hence,  cast-iron  cannot  be  safely  used  for  gun- 
carriages,  or  the  revetments  of  fortifications. 

462.  Effect  on  wrought-iron.  The  effect  produced 
by  a*  projectile  striking  against  a  mass  of  wrought-iron 
is  similar  to  that  produced  on  cast-iron ;  but,  in  conse- 
quence of  its  greater  toughness,  softness,  and  malleability, 
the  fragments  are  not  so  readily  formed,  the  indentation 
is  deeper,  and  a  portion  of  the  compressed  metal  is  thrust 
aside,  raising  the  edge  of  the  indentation  into  a  burr. 

The  superior  toughness  and  cheapness  of  this  metal 
have  suggested  its  application  as  a  covering  for  vessels 
of  war,  and  numerous  trials  are  now  in  progress  among 
the  principal  naval  powers  of  Europe  to  test  its  suitable- 
ness for  this  purpose. 

The  following  conclusions  have  been  drawn  from  the 
trials  thus  far  completed  in  England  :* 

1st.  Thin  plates  of  wrought-iron  may  serve  as  a  pro- 
tection against  shells  of  any  size.  The  plates  may  be 
penetrated,  but  the  shells  are  broken  by  the  impact, 
and  therefore  rendered  harmless,  if  the  woodwork  be- 
hind the  plates  be  sufficient  to  arrest  the  fragments. 

2d.  The  thickness  of  a  wrought-iron  plate  necessary 

*  Vide  Sir  Howard  Douglas,  Naval  Gunnery,  5th  edition. 


EFFECT    ON    WROUGHT-IRON.  473 

to  resist  heavy  solid  shot  moving  with  high  velocities  is 
not  less  than  4J>  inches. 

The  resistance  is  very  much  increased  by  supporting 
the  plate  in  rear  with  a  mass  of  stout  timber,  or  some 
other  elastic  substance.  A  plate  of  wrought-iron  6  feet 
square  and  8  inches  thick,  standing  in  an  inclined  posi- 
tion against  a  wall,  was  broken  up  by  twelve  68-pdr. 
shots  fired  with  a  charge  of  16  pounds  of  powder,  at 
distances  of  400  and  600  yards. 

3d.  Rifle  projectiles,  having  more  momentum,  are 
effective  at  greater  distances  than  round  shot. 

4th.  Though  iron-plated  vessels  have  been  made  which 
are  capable  of  resisting  isolated  shots  from  heavy  can- 
non,* none  have  yet  been  made  fulfilling  all  the  condi- 
tions of  flotation,  stability  and  manageability,  which  are 
capable  of  resisting  a  simultaneous  and  concentrated 
cannonade  of  68-pdr.  shot,  or  of  rifle  projectiles.  Such 
vessels  may  afford  shelter  for  their  crews  for  a  time,  and 
may  pass  sea-coast  batteries  with  comparative  impunity, 
but  it  would  not  be  prudent  for  them  to  take  up  a  posi- 
tion near  a  place  guarded  by  powerful  cannon,  for  the 
purpose  of  cannonading  it,  more  especially  if  the  com- 
mand of  the  land-batteries  gives  a  j)lunging  fire  on  the 
vessels. 

The  results  of  the  numerous  trials  have  induced  the 
English  government  to  construct  several  plated  vessels ; 
one  of  which  is  to  serve  the  double  purpose  of  a  frigate 


*  It  remains  to  be  determined  whether  vessels  can  bo  conveniently  covered  with 
sufficient  thickness  of  iron  to  resist  the  crushing  effect  of  the  enormous  projectiles 
of  the  15-inch  columbiad,  or  in  other  words,  is  it  practicable  to  increase  the  resist- 
ance of  such  iron  coverings  to  keep  pace  with  the  increase  in  the  destructive  power 
of  projectiles  ?  Captain  Rodman  claims,  with  a  show  of  reason,  that  if  the  15-inch  gun 
bo  not  sufficient  for  this  purpose,  much  larger  ones  can  be  made,  that  will  suffice. 


474  EFFECTS    OF   PROJECTILES. 

and  steam  ram.  The  sides  of  this  frigate  are  composed 
of  20  inches  of  solid  teak-wood,  covered  on  the  inside 
with  plates  £  inch  thick,  of  the  best  wrought-iron,  and 
on  the  outside  with  plates  4£  inches  thick,  of  the  same 
material.  The  exterior  plates  are  15  feet  long  and  3 
wide,  and  are  united  together  by  a  tongue  and  groove 
joint. 

Late  experiments  at  Shoeburyness  show,  that  beyond 
a  thickness  of  f-  of  an  inch,  semi-steel  plates  do  not 
resist  the  impact  of  projectiles  as  well  as  those  made  of 
good  wrought-iron,  but  for  less  than  this  thickness,  they 
offer  a  much  greater  resistance.  It  was  shown  at  the 
same  time  that,  whatever  be  the  angle  offered  by  the 
surface  of  the  target,  the  fracture  made  by  the  Arm- 
strong projectiles  was  the  same,  although  the  shape 
differed  somewhat  with  the  angle ;  this,  probably,  was 
the  result  of  instantaneous  concussion. 

Cast  and  wrought  iron  projectiles,  fired  with  high 
velocities  against  thick  wrought-iron  plates,  are  gen- 
erally broken  by  impact,  while  those  of  puddled  steel 
and  homogeneous  iron  are  not  much  affected  by  it. 

463.  Effect  on  wood.  The  effect  of  a  projectile  fired 
against  wood  varies  with  the  nature  of  the  wood  and 
the  direction  of  the  penetration.  If  the  projectile 
strike  perpendicular  to  the  fibres,  and  the  fibres  be 
tough  and  elastic,  as  in  the  case  of  oak,  a  portion  of 
them  are  crushed,  and  others  are  bent  under  the  press- 
ure of  the  projectile,  but  regain  their  form  as  soon  as 
it  has  passed  by  them.  It  is  found  that  a  hole,  formed 
in  oak  by  a  ball  4  inches  in  diameter,  closes  up  again, 
so  as  to  leave  an  opening  scarcely  large  enough  to 
measure  the   depth   of  penetration.      The  size   of  the 


EFFECT    ON    EARTH.  475 

hole  and  the  shattering  effect  increase  rapidly  for  the 
larger  calibres.  A  9-inch  projectile  has  been  found  to 
leave  a  hole  that  does  not  close  up,  and  to  tear  away 
large  fragments  from  the  back  portion  of  an  oak  target 
representing  the  side  of  a  ship  of  war,  the  effect  of 
which,  on  a  vessel,  would  have  been  to  injure  the  crew 
stationed  around,  or,  if  the  hole  had  been  situated  at 
or  below  the  water  line,  to  have  endangered  the  vessel. 
If  penetration  take  place  in  the  direction  of  the 
fibres,  the  piece  is  almost  always  split,  even  by  the 
smallest  shot,  and  splinters  are  thrown  to  a  considera- 
ble distance. 

In  consequence  of  the  softness  of  white  pine,  nearly 
all  the  fibres  struck  are  broken,  and  the  orifice  is  nearly 
the  size  of  the  projectile ;  for  the  same  reason,  the 
effects  of  the  projectile  do  not  extend  much  beyond 
the  orifice ;  pine  is  therefore  to  be  preferred  to  oak  for 
structures  that  are  not  intended  to  resist  cannon  pro- 
jectiles, as  block-houses,  <fcc. 

464.  Effect  on  earth.  To  determine  the  shape  of 
the  orifice  made  by  a  projectile  in  a  substance  which 

retains  its  form,  let 
C  C\  fig.  152,  repre- 
sent a  projectile  pene- 
trating the  substance 
Fis-  152«  in    the   direction    of 

the  arrow.  The  friction  of  the  particles,  as  they  move 
over  the  surface  of  the  projectile,  depends  on  the  nor- 
mal pressure,  which  diminishes  from  the  point  imme- 
diately in  front  to  those  on  the  extreme  sides,  where  it 
is  nothing.  For  the  distances  A  C  and  A  C ,  the  fric- 
tion will  be  so  great  that  the  included  particles  will 


476  EFFECTS    OF   PROJECTILES. 

not  move  over  the  surface,  but  they  will  constitute 
the  base  of  a  cone  of  matter,  C  A.  C,  that  will  be 
pushed  forward  in  front  of  the  projectile.  Particles 
situated  beyond  C  and  C  will  be  thrown  off  from 
the  surface,  in  a  tangential  direction,  with  a  velocity 
depending  on  the  position  of  the  particle  and  the  ve- 
locity of  the  projectile. 

Take  the  case  of  the  particle  adjacent  to  C.  Let 
D  C  represent  the  velocity  of  the  projectile,  and  F  C 
the  direction  of  the  tangent;  the  side  C  E,  of  the 
rectangle  constructed  on  D  CJ  will  represent  the  veloc. 
ity  impressed  on  the  particle,  in  the  direction  at  right 
angles  to  the  penetration. 

The  velocity  CE  varies  with  the  velocity  D  E,  which 
rapidly  diminishes  from  the  moment  of  striking.  It 
follows,  that  an  element  of  the  surface  of  the  orifice 
formed  by  a  projectile  in  a  plastic  substance  is  curved, 
and  has  its  convexity  turned  toward  the  projectile. 

Earth  possesses  advantages  over  all  other  materials 
as  a  covering  against  projectiles;  it  is  cheap  and  easily 
obtained,  it  offers  considerable  resistance  to  penetration, 
and  to  a  certain  extent  regains  its  position  after  dis- 
placement. It  is  found  by  experience  that  a  projectile 
has  very  little  effect  on  an  earthen  parapet,  unless  it 
passes  completely  through  it,  and  that  injury  done  by 
the  enemy's  artillery  by  day  can  be  promptly  repaired 
at  night.  Wherever  masonry  is  liable  to  be  breached, 
it  should  be  masked  by  earthworks. 

465.  Penetration.  The  resistance  which  a  projectile 
encounters  in  penetration,  arises  from  the  cohesion  and 
inertia  of  the  particles,  and  the  friction  of  the  particles 
against  the  surface  of  the  projectile. 


PENETEATION.  477 

To  obtain  an  expression  for  the  penetration,  we  will 
suppose  that  the  resistance  is  proportional  to  the  area 
of  the  cross-section  of  the  projectile,  and  independent 
of  the  velocity.  Let  E  be  the  penetration  expressed  in 
calibres,  D  the  density  of  the  projectile,  v  its  velocity 
at  the  commencement  of  penetration,  r  the  radius  of  the 
projectile,  and  H  the  constant  resistance  experienced  by 
a  unit  of  surface ;  the  quantity  of  work  done  in  over- 
coming the  resistance  is, 

nr\U.  2r.fi;  ^^Vi) 

and  the  living  force  of  the  projectile  is  ^  ^  /v/i  c 

4    3D  2 

-nr6 V  . 

3      9 

But  the  living  force  is  equal  to  twice  the  quantity  of 
work ;  hence  we  have, 

3     g 

by  making  K=  we  obtain, 

ZKg 

U=Xv2D. 

Take  another  projectile,  having  a  velocity  v',  a  den- 
sity d,  and  a  penetration  e,  and  we  have  the  expression, 
e=  Kv^d.  Dividing  the  preceding  expression  by  this, 
member  by  member,  and  we  have, 

vjd 
that  is  to  say,  the  penetrations  of  different  spherical  pro- 
jectiles into  a  given  substance,  are  proportional  to   the 
squares  of  the  velocities  of  impact,  and  to  the  diameters* 
and  densities  of  the  projectiles. 

*  The  diameters  of  all  service  projectiles  are  given  in  the  Ordnance  Manual. 


478  EFFECTS    OF   PEOJECTILES. 

Knowing,  therefore,  the  penetration  e,  for  a  given 
velocity  and  projectile,  we  can  obtain  the  penetration 
E,  for  another  projectile  and  velocity.  Let  e  represent 
the  penetration  for  a  shot  moving  with  a  velocity  of 
1,650  feet,  the  expression  becomes, 

1650  d 
This  formula  has  been  found  by  experience  to  give, 
with  sufficient  accuracy,  the  penetration  of  projectiles  in 
hard  substances,  as  wood,  cast-iron,  and  masonry,  for  all 
velocities  up  to  1,000  feet  per  second.  The  following 
penetrations,  or  values  of  £,  have  been  found  for  solid 
shot  moving  with  a  velocity  of  1,650  feet,  viz. : 

Cast-iron  (depending  on  its  nature),      '  \  to  \ 
Lead,         .         .  '       .         .         .  3j-  to  3£ 

Calcareous  rocks  (particular  kind),         .         2 
Masonry  of  good  quality,  .         .         .4 

"         rubble,  .         .         .         5  to  5| 

"         brick,  .         .         .'       .         .8 

Substituting  the  above  values  of  e  in  the  value  of  E, 
we  obtain  the  penetrations,  expressed  in  terms  of  the 
diameter  of  the  projectile,  for  any  velocity  not  exceed- 
ing 1,000  feet. 

Solid  shot  are  broken,  when  fired  against  very  hard 
substances,  with  charges  exceeding  the  following,  viz.  :* 

Against  cast-iron,        .         .         .  T~ 

lead,  1 

"        calcareous  rock  (oolitic),  .             } 

"        masonry,  I 

*  Some  shot  resist  these  charges. 


PENETRATION.  479 

The  velocity  v,  is  the  velocity  which  the  projectile 
possesses  at  the  commencement  of  penetration;  if  the 
piece  be  situated  at  a  distance,  it  is  necessary  to  deter- 
mine the  remaining  velocity,  by  making  allowance  for 
the  resistance  of  the  air.     Equation  (20),  page  408. 

v2     D 
Wood.     The  formula  E—  e  — >  may  be  used  to 

16502  d 
calculate  penetrations  in  wood,  for  velocities  which  do 
not  exceed  1,000  feet,  making   use   of  the  following 
values  of  e  for  penetrations  perpendicular  to  the  fibre  : 

For  oak  of  ordinary  quality,     .         .       e=.Vl\ 

"    elm, 16 

"    pine, 23 

For  velocities  exceeding  1,000  feet,  the  formula  just 
employed  gives  results  which  are  too  large ;  from  this 
it  is  inferred  that  penetration  really  increases  less  rapid- 
ly than  the  square  of  the  velocity. 

Earth.  In  the  experiments  made  at  Metz,  in  1834, 
on  various  kinds  of  earths,  it  was  found  necessary  to 
modify  this  expression  for  penetration.  Calling  p  the 
weight  of  the  powder,  and  m  the  weight  of  the  projec- 
tile, the  expression  becomes,  for  all  charges  between  4- 
and  TV, 

_ loK1+480x£)i>  y{l+^^D 

■E-elog^(l-\-4:S0x^)d~e ,        2.20683  d' 

The  following  values  of  e,  for  a  charge  of  |,  were 
found  for  different  earths : 

For  sand  mixed  with  gravel,  .         6=sl0j- 

For  earth,  settled,  .         .         .         Wj 


480  EFFECTS    OF   PROJECTILES. 

Potter's  clay,  saturated  with  water,         .     36 
Light  earth  newly  dug  over,       .         .         32-^ 

The  penetration  being  given  in  terms  of  the  weight 
of  the  powder  and  projectile,  the  piece  should  be  suffi- 
ciently long  to  obtain  the  full  force  of  the  charge,  or 
from  17  to  20  calibres;  or,  in  other  words,  the  expres- 
sion is  only  suited  to  field  and  siege  guns. 

In  general,  sand,  sandy  earth  mixed  with  gravel,  small 
stones,  chalk,  or  tufa,  resist  shot  better  than  the  produc- 
tive earths,  or  clay,  or  earth  that  retains  moisture. 

Water.      To    obtain   penetration   in   water,   replace 

480^.  by  4800^-,  and  make  e  equal  to  275  calibres. 
m  m 

In  some  late  experiments,  it  was  found  that  the  Whit- 
worth  projectile  had  sufficient  force,  at  short  distances, 
to  pass  through  33  feet  of  water  and  then  penetrate  12 
or  14  inches  of  oak  beams  or  scantling.  The  penetra- 
tion of  a  rifle-projectile  in  water,  depends  much  on  the 
direction  of  its  axis  with  respect  to  penetration,  for  in- 
stance, penetration  rapidly  diminishes  at  long  distances, 
as  the  axis  of  the  projectile  strikes  the  surface  of  the 
water  under  a  diminished  angle. 

466.  Effect  on  masonry.  The  effect  of  a  projectile 
against  masonry,  is  to  form  a  truncated  conical  hole, 

terminated  by  another  of  a 
cylindrical  form.     (See  fig. 
153.)  The  material  in  front 
of  and  around  the  projec- 
ts- 153-  •  tile  is  broken  and  shatter- 
ed, and  the  end  of  the  cylindrical  hole  even  reduced  to 
powder.     Pieces  of  the  masonry  are  sometimes  thrown 


BREACHING.  481 

50  or  60  yards  from  the  wall.  The  elasticity  developed 
by  the  shock,  reacts  upon  the  projectile,  sometimes 
throwing  it  back  150  yards,  so  as  to  be  dangerous  to 
persons  in  a  breaching  battery.  The  exterior  opening 
varies  from  4  to  5  times  the  diameter  of  the  projectile, 
and  the  depth,  as  we  have  seen,  varies  with  the  size  and 
density  of  the  projectile,  and  its  velocity. 

With  charges  of  -*-,  -|,  |,  and  |,  a  projectile  ceases  to 
rebound  from  a  wall  of  masonry  when  the  angles,  formed 
by  the  line  of  fire  and  the  surface  of  the  wall,  exceed 
20°,  24°,  33°,  43°,  respectively.  With  these  angles,  the 
angle  of  reflection  is  much  greater  than  the  angle  of 
incidence,  and  the  velocity  after  impact  is  very  slight. 

When  a  projectile  strikes  against  a  surface  of  oak,  as 
the  side  of  a  ship,  it  will  not  stick  if  the  angle  of  inci- 
dence be  less  than  15°,  and  if  it  do  not  penetrate  to  a 
depth  nearly  equal  to  its  diameter. 

Solid  cast-iron  shot  break  against  granite,  but  not 
against  freestone  or  brick.  Shells  are  broken  into  small 
fragments  against  each  of  these  materials. 

467.  Breaching.  Escalade  being  ordinarily  very  dif- 
ficult, particularly  when  the  besieged  are  aware  of  the 
intention  of  the  besiegers,  the  latter  are  generally  com- 
pelled to  destroy  a  portion  of  the  face  of  the  work  to 
obtain  an  entrance.  Such  an  opening  is  called  a  breach; 
and  to  effect  it  with  artillery,  particularly  in  a  well- 
constructed  work,  where  no  part  of  the  scarp-wall  is 
visible  from  the  adjacent  ground,  within  effective  range 
of  siege-cannon,  breaching-batteries  are  established  either 
on  the  crest  of  the  covered  vjay,  or  on  the  glacis. 

When  the  walls  of  fortified  places  were  very  high 

and  not  supported  by  terraces  or  ramparts,  stone  pro- 
31 


482  EFFECTS    OF    PKOJECTILES. 

jectiles  were  used.  From  the  want  of  sufficient  hardness 
in  these  projectiles,  the  besiegers  were  forced  to  com- 
mence battering  at  the  top  of  the  wall  where  the  least 
resistance  was  offered,  and  gradually  to  lower  the  shot 
until  the  breach  reached  the  wrecks  already  formed  at 
the  base  of  the  wall.  When  the  style  of  fortification 
was  changed,  this  operation  became  very  laborious,  the 
ascent  was  very  steep,  and  the  breach  was  often  imprac- 
ticable. This  method  was  abandoned  and  mining  sub- 
stituted. Iron  projectiles  superseded  stone,  and  then  a 
more  rapid  mode  of  effecting  a  practicable  breach  was 
suggested  and  confirmed  by  experience. 

Vauban  recommended  increasing  the  size  of  the  hole 
first  formed,  by  continually  firing  at  its  sides  until  the 
wall  should  fall ;  but  the  ball  was  found  to  glance  into 
it,  and  injure  but  slightly  the  untouched  portion  of  the 
revetment.  The  best  mode,  however,  as  found  by  ex- 
periment, is  to  cut  the  wall  up  into  detached  parts,  by 
making  one  horizontal  and  several  vertical  fissures,  and 
battering  each  part  down  separately.     (Fig.  154.) 

The  easiest  mode  of  making 

the  cut  is  to   direct  the  shots 

upon  the  same  line,  and  form 

a   series    of  holes   (Jig.  154),  a 

Fig.  154.  little  greater   than   a   diameter 

apart,  and  then  to  fire  a  second  series  of  shots,  directed 

at  the  intervals  between  the  first,  and  so  on,  until  an 

opening  is  made  completely  through  the  wall. 

The  first  cut  is  made  horizontally,  and  finished,  which 
will  be  known  by  the  earth  falling  through  it ;  the  ver- 
tical cuts  are  then  made,  there  being  one  at  each  end  of 
the  intended  breach.     These  cuts  are  commenced  at  the 


BREACHING.  483 

horizontal  cut,  and  raised  until  the  wall,  isolated  from 
its  supports,  sinks,  overturns,  and  breaks  into  pieces, 
which  become  covered  by  falling  earth.  If  the  earth 
be  sustained  by  its  tenacity,  loaded  shells  are  fired  into 
it,  which,  acting  like  small  mines,  cause  it  to  fall,  and 
make  the  breach  practicable,  or  of  easy  ascent. 

If  the  portion  of  the  wall  between  the  vertical  cuts 
should  not  be  overthrown  by  the  pressure  of  the  earth 
behind,  it  must  be  detached  by  a  few  volleys  of  solid 
shot,  fired  at  its  centre.  This  will  speedily  bring  it 
down  in  a  mass.  The  moment  the  wall  is  down,  and 
the  parapet  destroyed,  the  breach  will  be  as  perfect, 
and  the  slope  as  easy  of  ascent,  as  it  can  be  made  by 
the  fire  of  the  batteries.  It  is  important  to  determine 
the  height  of  the  horizontal  cut  above  the  bottom  of 
the  ditch,  for,  if  this  height  be  not  properly  chosen,  the 
breach  may  be  difficult,  if  not  impracticable.  If  too 
high,  the  ramp  composed  of  the  debris  will  be  inter- 
cepted by  a  portion  of  the  wall ;  if  too  low,  the  open- 
ing will  be  masked  by  the  debris,  and  the  formation  of 
the  cut  impeded.  The  most  suitable  height  is  nearly 
equal  to  the  thickness  of  the  wall  where  the  cut  is 
established.  The  thickness,  where  not  known,  can  be 
deduced  from  the  dimensions  necessary  to  be  given 
to  the  wall,  to  resist  the  pressure  of  the  earth  of  the 
rampart  and  parapet. 

The  time  necessary  to  make  a  breach,  depends  on  the 
size  of  the  breach  to  be  made,  the  material  of  the  scarp, 
the  number  of  guns,  &c.  For  a  breach  of  20  to  30 
yards  in  length,  at  forty  yards  from  the  battery,  1,500 
shot  of  large  calibre  will  be  required ;  but  when  the 
battery  is  at  a  greater  distance,  a  greater  number  of 


484  EFFECTS    OF   PROJECTILES. 

projectiles  will  be  necessary,  on  account  of  the  dimin- 
ished accuracy  and  penetration.  Thus,  at  500  or  600 
yards  9,000  to  10,000  may  be  needed. 

Rules,  The  following  general  rules  should  be  ob- 
served in  firing  to  effect  a  breach : — 

1.  Ascertain  as  accurately  as  possible  the  widths  of 
the  ditch  and  covered  way,  the  height  of  the  scarp- 
wall,  the  thickness  of  the  parapet,  the  height  of  the 
counterscarp,  and  crest  of  the  covered  way.  By  the 
aid  of  a  profile  that  can  be  constructed  from  this  data, 
determine  the  height  of  the  horizontal  cut  to  be  made 
in  the  scarp,  so  that  the  slope  of  the  ramp  shall  be  45°. 
This  height  should  never  be  below  a  fourth  of  that  of 
the  scarp,  and,  to  avoid  interference  from  the  wrecks,  it 
should  be  nearly  equal  to  the  presumed  thickness  of  the 
wall  at  the  cut.  If  the  ditch  be  a  wet  one,  commence 
cutting  at  the  water's  edge. 

2.  From  the  number  of  pieces  with  which  the  bat- 
tery is  to  be  armed,  and  the  length  of  the  breach,  de- 
termine the  field  of  fire  of  each  piece,  and  the  length  of 
cut  that  it  is  to  make. 

3.  Ascertain  the  angle  of  elevation,  or  depression,  for 
each  piece,  to  strike  the  cut,  and  mark  it  unalterably  on 
the  elevating  screw. 

4.  Direct  each  piece  on  the  right  or  left  of  the  part 
to  be  cut,  and  space  the  shot  from  right  to  left,  or 
from  left  to  right,  at  If  to  1^  yards  for  the  24-pdr., 
and  1  yard  for  the  18-pdr.  Mark  on  the  platform  the 
direction  of  the  stock  and  wheels  at  each  shot.  Re- 
turning then  from  left  to  right,  or  from  right  to  left, 
fire  at  the  middle  of  the  intervals  left  by  the  first  shot, 
and  mark  the  directions  as  before.     Continue  this  firing 


i 
BREACHING    WITH   RIFLE-CANNON.  485 

regularly  at  the  most  prominent  points,  and  make  the 
cut  progress  equally  throughout. 

5.  Fire  at  the  horizontal  cut  until  the  earth  falls 
throughout  the  cut. 

6.  Determine  the  number  of  vertical  cuts  to  be  made, 
at  the  rate,  at  most,  of  one  to  a  piece,  without  spacing 
more  than  10  yards  apart,  in  order  that  no  part  shall 
be  sustained  by  more  than  one  counterfort.  Fire  as  in 
the  case  of  the  horizontal  cut,  commeDcing  at  the  upper 
line. 

7.  See  that  the  extreme  vertical  cuts  progress  as 
rapidly  as  the  interior  ones,  and  direct  the  adjoining 
guns  upon  them  if  necessary. 

8.  If  the  wall  do  not  fall  after  the  cuts  are  made, 
fire  a  few  volleys  at  the  middle  of  the  spaces  thus  out- 
lined. 

9.  After  the  fall  of  the  wall,  break  down  the  coun- 
terforts, and,  if  time  or  resources  permit,  replace  the 
guns  by  8-inch  howitzers,  and  fire  upon  the  earth  with 
loaded  shells,  or  fire  shells  from  the  guns. 

468.  Breaching  with  rifle-cannon.  The  superior 
breaching-power  of  rifle-projectiles  depends  not  only 
on  penetration,  but  on  great  accuracy  of  flight,  whereby 
they  can  be  quickly  concentrated  on  any  desired  point. 
This  has  been  satisfactorily  shown  by  an  experiment 
lately  made  in  England  with  Armstrong  guns,  throw- 
ing projectiles  of  40,  80,  and  100  lbs.  weight,  respec- 
tively. 

The  subject  of  the  experiment  was  a  Martello  tower, 
30  feet  high,  and  48  feet  diameter;  the  walls  were 
from  7  feet  3  inches  to  10  feet  thick,  of  solid  brick 
masonry  of  good   quality.      The   distance   was    1,032 


486  EFFECTS    OF    PROJECTILES. 

yards — more  than  twenty  times  the  usual  breaching 
distance. 

The  80-pdr.  shot  passed  completely  through  the  ma- 
sonry (7  feet  3  inches),  and  the  40-pdr.  shot  and 
100-pdr.  percussion  shells  lodged  in  the  brick- work,  at 
a  depth  of  five  feet.  After  firing  170  projectiles,  a 
small  portion  of  which  were  loaded  shells,  the  entire 
land-side  of  the  tower  was  thrown  down,  and  the  inte- 
rior space  was  filled  with  the  debris  of  the  vaulted 
roof,  forming  a  pile  which  alone  saved  the  opposite 
side  from  destruction. 

It  is  not  presumed  that  the  introduction  of  rifled  siege 
cannon  will  change  the  principles  of  breaching,  as  laid 
down  in  the  preceding  section,  but  it  will  compel  the 
defence  to  strengthen  his  works  by  the  various  appli- 
ances known  to  the  engineer's  art. 

469.  Effect  of  buiiet§.  The  penetrations  of  the  rifle- 
musket  bullet,  in  a  target  made  of  pine  boards,  one  inch 
thick,  are  as  follows : — 

At    200  yards 11  inches. 

"     600  yards 6|     « 

"  1,000  yards 3|     a 

From  experiments  made  in  Denmark,  the  following  re- 
lations were  found,  between  the  penetration  of  a  bullet 
in  pine  and  its  effects  on  the  body  of  a  living  horse,  viz. : 

1st.  When  the  force  of  the  bullet  is  sufficient  to  pene- 
trate .31  in,  into  pine,  it  is  only  sufficient  to  produce  a 
slight  contusion  of  the  skin. 

2d.  "When  the  force  of  penetration  is  equal  to  0.63 
in.,  the  wound  begins  to  be  dangerous,  but  does  not 
always  disable. 


EFFECT    OF   BULLETS.  487 

3d.  When  the  force  of  penetration  is  equal  to  1.2 
inch,  the  wound  is  very  dangerous. 

It  will  thus  be  seen,  that  the  present  bullet  is  capable 
of  producing  very  dangerous  wounds  at  a  much  greater 
distance  than  1,000  yards. 

A  rope  matting  or  mantlet,  3^  inches  thick,  is  found 
to  resist  small- arm  projectiles  at  all  distances ;  it  may, 
therefore,  be  employed,  as  it  was  at  the  siege  of  Sebas- 
topol,  to  screen  the  gunners  of  siege  batteries  from  the 
enemy's  riflemen, 

A  field-cannon  ball  has  sufficient  force  to  disable 
seven  or  eight  men  at  a  distance  of  900  yards.  It  is 
stated  that  a  single  cannon-ball,  at  the  battle  of  Zorn- 
dorf,  disabled  forty-two  men — distance  not  given. 


488  EMPLOYMENT    OF    FIELD-AKTILLEKY. 

CHAPTER  XII. 
EMPLOYMENT  OF  FIELD-ARTILLERY.* 

470.  Oreatest  range.  The  extreme  range  of  field-ar- 
tillery has  been  stated  to  be  about  3,000  yards  ;f  a  some- 
what greater  range  than  this  can  be  obtained  by  sinking 
the  trail  of  the  carriage  into  the  ground,  thereby  in- 
creasing the  elevation  of  the  piece;  but  in  consequence 
of  the  great  strain  thus  thrown  upon  the  carriage,  and 
the  great  inaccuracy  of  the  fire,  it  should  be  seldom  re- 
sorted to,  unless  it  be  to  produce  a  moral  effect  on  an 
army  in  retreat,  or  passing  a  defile.  If  employed  against 
an  enemy  acting  on  the  offensive,  it  would  have  the  ef- 
fect, from  its  extreme  inaccuracy,  to  give  him  increased 
confidence. 

In  general  terms,  firing  at  long  range  should  only  be 
employed  when  the  nature  of  the  ground,  or  the  short- 
ness of  the  time,  does  not  permit  a  nearer  approach  to 
the  object;  and  it  should  always  cease  when  the  object 
of  the  fire  is  attained. 

Effective  range.  The  greatest  effective  range  of  field- 
artillery  varies  from  1,400  to  1,800  yards.  Batteries  of 
position  belonging  to  an  army  acting  on  the  defensive, 
should  open  fire  at  a  distance  of  1,300  or  1,400  yards. 
The  object  of  this  fire  is  not  so  much  to  arrest,  as  to  re- 
tard, the  movement  of  the  enemy,  and  compel  him  to 
establish  batteries  to  cover  his  approach.     The  distances 

*  Vide  Decker's  Instruction  Pratique,  &c. 

f  The  ranges  in  this  chapter  refer  to  smooth-bored  rather  than  rifled  guns.  The 
principles,  however,  involved  in  it,  are  equally  applicable  to  both. 


GREATEST    RANGE.  489 

should  be  carefully  estimated,  and  the  firing  should  take 
place  slowly,  in  order  that  the  effect  of  each  shot  may 
l>e  observed,  and  the  aim  corrected,  if  necessary. 

Rapid  and  continuous  firing  should  commence  at  a 
distance  of  800  or  1,000  yards;  the  attacking  party 
should,  at  the  same  time,  establish  his  batteries  to  cover 
the  deployment  of  his  columns,  and  to  enable  him  to 
make  the  necessary  preparations  for  attack. 

At  a  distance  of  600  or  700  yards,  or  point-blank 
distance,  the  fire  becomes  very  destructive;  generally 
not  more  than  six  or  eight  shots  can  be  fired  before  one 
of  the  parties  will  either  advance  or  retire.  As  the 
distance  closes,  canister-shot  should  replace  round-shot, 
which  generally  ends  in  producing  disorder. 

Against  infantry.  Formerly  artillery  could  take  up 
a  position  about  300  or  400  yards  in  front  of  infantry 
without  serious  loss;  but  the  introduction  of  the  rifle- 
musket  has  produced  a  very  great  change  in  the  relative 
powers  of  these  two  arms.  The  experiments  made  at 
the  musketry-school  at  Hythe,  show  conclusively  that 
artillery  cannot  long  maintain  a  position  within  half  a 
mile  of  properly  instructed  skirmishers,  as  the  fire  of 
rifle-musketry  at  this  distance  is  as  effective  as  that  of 
canister  at  250  or  300  yards. 

Should  the  surface  of  the  ground  be  broken,  or  of 
such  nature  as  to  afford  shelter  to  skirmishers,  the  pre- 
ponderance will  be  still  more  in  their  favor.  And  should 
the  artillery  not  succeed  in  silencing  the  fire  of  the 
skirmishers  by  well  served  case-shot,  it  will  be  obliged 
to  retire  beyond  the  reach  of  the  rifles,  and  trust  to  the 
effect  of  round  and  spherical  case-shot  upon  the  enemy's 
masses. 


490  EMPLOYMENT    OF    FIELD- ARTILLEKY. 

Against  cavalry.  Cavalry,  in  charging  upon  an 
enemy  situated  at  a  distance  of  1,000  yards,  pass  over 
the  intervening  space  in  about  seven  minutes.  Each 
piece  may  fire  nine  rounds  of  solid  shot,  or  spherical 
case-shot,  in  the  first  400  yards,  two  solid  and  three 
canister  shot  in  the  next  400  yards,  and  two  rounds 
of  canister-shot  while  passing  over  the  remaining  200 
yards,  making  a  total  of  eleven  round  and  five  canister 
shot.  Neither  spherical  case-shot  nor  shells  should  be 
fired  against  cavalry  in  rapid  motion ;  and  care  should 
be  taken  not  to  cease  firing  solid  shot  too  soon  in  order 
to  commence  firing  canister. 

471.  Employment  of  different  kinds  of  Are.  The  fol- 
lowing circumstances  should  be  known,  to  enable  the 
artillerist  to  select  the  most  suitable  fire  for  a  particular 
occasion:  1st.  The  distance  of  the  enemy.  2d.  The 
conformation  and  quality  of  the  intervening  ground. 
3d.  The  formation  of  the  enemy,  as  far  as  can  be  seen 
or  judged  of. 

Direct  fire.  Direct  fire  should  be  employed  wherever 
the  surface  of  the  ground  is  uneven  and  the  quality  of 
the  soil  varied,  or  wherever  a  portion  fired  over  is 
smooth  and  the  remainder  broken,  or  the  soil  soft  and 
light.  There  are  other  special  cases  where  direct  fire 
should  be  employed : 

1st.  When  the  enemy  is  so  situated  as  to  conceal  the 
depth  of  his  formation;  otherwise  the  ground  in  rear 
of  his  front  line  may  be  such  that  the  ricochet  will  not 
take  effect ; 

2d.  When  the  enemy  is  about  to  pass  a  defile,  and 
the  head  of  the  column  only  is  seen ;  or  when  the 
depth  of  the  column  can  be  seen,  by  being  commanded 


EMPLOYMENT  OF  DIFFERENT  KINDS  OF  FIRE.  491 

or  overlooked;  in  this  case,  the  projectile  which  would 
miss  the  head  might  strike  the  middle  or  the  rear  of  the 
column ; 

3d.  It  should  be  employed  in  all  sustained  cannon- 
ades, because  the  effect  of  its  shots  can  be  more  easily 
distinguished  than  that  produced  by  the  shots  of  a 
rolling  fire.  The  aim  should  be  corrected  by  observing 
the  point  of  fall  of  the  projectile;  and,  for  this  purpose, 
it  is  desirable  to  take  the  mean  of  three  shots.  If  a 
rolling  fire  be  employed  under  these  circumstances,  the 
character  of  the  ground  and  formation  of  the  enemy 
may  be  such,  that  the  cannonade  may  be  carried  on  for 
hours  without  knowing  what  effect  is  produced. 

To  produce  good  results  with  direct  fire,  it  is  abso- 
lutely necessary  to  ascertain  the  exact  distance  of  the 
enemy,  which  can  only  be  done  by  a  practised  eye. 
This  circumstance  will  be  appreciated  when  we  con- 
sider that,  if  a  shot  only  strike  the  ground  fifteen  yards 
in  front  of  a  target  six  feet  high,  it  will  pass  completely 
over  it. 

When  the  object  is  not  on  the  same  level  with  the 
piece,  the  character  of  the  fire  will  be  determined  by 
the  nature  of  the  intervening  ground. 

If  the  surface  be  uniform,  and  have  an  inclination 
to  the  horizon  not  exceeding  15°,  above  or  below,  no 
change  need  be  made  in  the  kind  of  fire,  or  elevation 
of  the  piece,  from  what  they  would  be  on  horizontal 
ground. 

If  the  enemy  be  posted  on  a  mountain,  or  in  a  valley, 
the  direct  fire  can  only  be  used.  As  it  is  often  difficult 
to  estimate  the  distance,  the  pieces  should  be  aimed 
with  great  precision,  and  the  point  of  fall  should  be 


492  EMPLOYMENT    OF   FIELD-AETILLEEY. 

carefully  noted ;  the  firing  should  be  deliberate,  and  it 
should  be  recollected  that  a  different  height  of  sight  is 
necessary  than  when  the  object  is  on  level  ground. 

472.  Ricochet  fire.  Ricochet  fire  should  never  be 
used  for  a  less  distance  than  1,000  yards,  even  when  the 
ground  is  favorable;  for,  in  order  that  this  fire  may 
produce  its  greatest  effect,  it  is  necessary  that  the  pro- 
jectile should  make  two  or  three  rebounds  in  front  of 
the  enemy,  which  it  rarely  does  at  a  less  distance  than 
1,000  or  1,100  yards.  If  the  ground,  for  300  or  400 
yards  in  front  of  the  pieces,  be  soft  and  uneven,  or  if  it 
be  soft  and  uneven  for  100  or  300  yards  in  front  of  the 
enemy,  rolling  fire,  which  is  a  species  of  ricochet  fire, 
cannot  be  employed  with  effect. 

Large  and  deep  objects,  as  a  mass  of  troops,  a  park, 
or  a  column  of  artillery  on  the  march,  are  the  most  suit- 
able objects  for  ricochet  fire,  as  these  objects  present 
several  lines,  one  behind  the  other. 

473.  canister  fire.  The  fire  of  canister  does  not 
always  produce  the  effect  anticipated  for  it,  for  the  fol- 
lowing reasons,  viz. : 

1st.  The  object  is  thought  to  be  nearer  than  it  really 
is,  and  the  firing  sometimes  commences  too  soon. 

2d.  The  danger  is  often  thought  to  be  more  imminent 
than  it  really  is,  and,  consequently,  proper  care  is  not 
observed  in  aiming. 

3d.  The  character  of  the  ground  is  not  properly  ap- 
preciated ;  and  too  much  confidence  is  reposed  in  the 
effect  of  the  projectiles  thrown  over  unfavorable  ground. 

474.  Field-howitzers.  The  extreme  range  of  shells 
fired  from  field-howitzers  has  been  stated  to  be  from 
2,500  to  3,000  yards.     The  deviation  of  shells  at  ex- 


LONG    RANGES.  493 

treme  distances  is  so  great  that  they  should  only  be 
employed  against  large  objects,  as  cities,  camps,  &c. 

The  greatest  effective  range  of  howitzer-shells  is  about 
1,500  yards ;  shells  should  only  be  employed  at  this 
distance  in  the  offence,  and  then,  rather  as  an  exception 
to  the  general  rule. 

The  gun  should  always  be  employed  when  capable  of 
producing  the  same  effect  as  the  howitzer. 

Shells  act  by  percussion,  by  explosion,  and  by  moral 
effect ;  and  they  should  be  employed  in  preference  to 
shot  under  the  following  circumstances,  viz. : 

1st.  When  the  enemy  is  stationary  and  under  cover. 

2d.  When  the  ground  is  much  broken,  or  cannot  be 
seen. 

3d.  When  troops  are  posted  in  woods. 

4th.  From  one  mountain  to  another. 

5th.  When  the  enemy  is  posted  on  higher  or  lower 
ground. 

6th.  When  on  a  road  leading  through  a  valley. 

7th.  For  incendiary  purposes. 

8th.  In  pursuit. 

9th.  Whenever  it  is  necessary  to  produce  a  moral 
rather  than  a  physical  effect. 

EMPLOYMENT  OF  SIEGE-CANNON. 

In  siege  operations,  the  same  fires  are  employed  as 
in  the  field,  but  under  different  circumstances.  The 
position  of  the  object  is  generally  fixed  and  known, 
and  there  is  sufficient  time  to  consider  the  best  means 
of  attaining  it. 

475.  Long  ranges.     The  greatest  range  of  the  24-pdr. 


494  EMPLOYMENT    OF    FIELD-ARTILLERY. 

siege-gun,  mounted  on  its  appropriate  carriage,  is  about 
3,500  yards;  but  the  defence  should  not,  without  good 
reason,  make  use  of  a  greater  distance  than  950  yards, 
or  point-blank  distance,  for  it  is  his  duty  to  economize 
his  ammunition,  if  it  cannot  be  replaced. 

It  will  be  proper  to  fire  at  a  reconnoitring  party 
at  a  distance  of  1,000  or  1,100  yards,  to  prevent  a 
nearer  approach,  and  against  strong  attacking  columns, 
provided  they  offer  sufficient  surface  to  render  the 
chances  of  hitting  probable. 

In  the  attack.  Firing  at  long  ranges,  on  the  part 
of  the  besiegers,  should  be  strictly  forbidden,  as  it 
would  disclose  to  the  enemy  the  proposed  front  of 
attack,  without  any  compensating  advantage. 

In  the  siege  service,  it  is  more  important  to  avoid 
useless  firing  than  in  the  field,  for  every  shot  that  does 
not  contribute  to  the  progress  of  the  attack,  by  weaken- 
ing the  defence,  is  a  shot  lost. 

476.  Enfilading  and  counter  flre§.  An  enfilading  fire 
is  directed  along  a  particular  portion  of  a  work,  and  a 
counter  fire  is  directed  toward  it. 

In  tlie  defence.  Solid  shot  are  used  in  enfilading  and 
counter  fires  under  the  following  circumstances : 

1st.  To  destroy  the  head  of  a  sap,  or  the  parapet  of 
a  trench. 

2d.  When  the  enemy  passes  from  the  first  to  the 
second  parallel,  and  before  he  has  completed  the  bat- 
teries intended  to  dismount  the  artillery  of  the  garrison. 

3d.  To  batter  vigorously  the  lateral  works  of  attack 
as  soon  as  they  are  finished. 

4th.  To  protect  and  support  sorties.  The  guns  placed 
on  the  parapet  of  the  place  keep  up  a  warm  fire  of 


ENFILADING    AND    COUNTER    FIRES.  495 

solid  shot  against  the  batteries  of  attack,  and  the 
heads  of  saps,  until  they  are  masked  by  the  troops 
making  the  sortie. 

5th.  To  prevent  the  enemy  from  following  too  closely 
upon  the  heels  of  the  party,  which,  having  made  the 
sortie,  are  returning,  successful  or  otherwise. 

6th.  From  the  guns  placed  on  the  flanks  of  the  bas- 
tions when  the  besiegers  attempt  to  pass  the  ditch ;  in 
this  case  the  fire  is  plunging. 

7th.  To  drive  the  besiegers  from  any  outwork  that 
they  may  have  taken. 

8th.  In  a  cannonade,  the  object  of  which  is  to  dis- 
mount the  besiegers'  guns. 

In  the  attach.  The  object  of  enfilading  fire  in  the 
attack  of  a  place,  is  to  rake  the  terrepleins  of  the 
faces,  curtains,  &c,  and  to  render  them  untenable ;  for 
this  purpose  the  batteries  should  be  established  on  the 
prolongation  of,  and  at  right  angles,  or  nearly  so,  with 
the  direction  of  the  part  to  be  enfiladed.  As  the  por- 
tion of  the  works  to  be  attained  is  not  commanded  by 
the  besiegers'  cannon,  enfilading  fire,  under  these  cir- 
cumstances, becomes  ricochet  fire,  the  nature  and  treat- 
ment of  which  have  already  been  described. 

Enfilading  and  counter  batteries  are  generally  es- 
tablished at  300  or  600  yards  from  the  place,  or  at  the 
first  and  second  parallels.  As  the  object  of  a  counter 
battery  is  to  silence  the  fire  of  the  place  by  dismount- 
ing the  guns,  its  pieces  should  be  directed  against  the 
embrasures. 

This  demands  great  care  in  aiming,  and  great  accuracy 
of  fire ;  the  heaviest  smooth-bored  or  rifled  guns  should 
therefore  be  employed  for  this  purpose. 


496  EMPLOYMENT    OF    FIELD-ARTILLERY. 

477.  Firing  in  breach.  When  the  besiegers  have 
approached  to  a  suitable  distance  to  commence  the 
breach,  the  opposing  artillery  will  have  been  silenced; 
but  they  will  be  subjected  to  flank  and  rear  fires, 
against  which  they  will  protect  themselves  by  traverses. 
Counter-batteries  will  also  be  established  with  the 
breaching- batteries,  the  object  of  which  will  be  to  silence 
the  artillery  bearing  on  the  breaching-batteries,  and  the 
passage  of  the  ditch.  The  method  of  forming  a  breach 
has  already  been  described. 

478.  Fire  of  ca§e-§hot.  Case-shot  should  be  employed 
in  the  defence  of  a  work  under  the  following  circum- 
stances, viz. : 

1st.  In  sorties,  where  field-artillery  can  be  employed. 

2d.  At  all  points  liable  to  sudden  attacks,  as  on 
avenues  leading  toward  gates,  or  on  bridges.  Pieces 
situated  on  the  flanks  are  particularly  suited  to  this 
fire. 

3d.  Against  the  gorge  of  an  outwork  which  the  enemy 
may  make  a  bold  attempt  to  seize.  For  this  purpose, 
pieces  on  the  curtains,  or  shoulder  angles,  should  be 
employed,  taking  care,  at  the  same  time,  not  to  fire  over 
works  occupied  by  the  defence. 

4th.  This  fire  may  be  safely  employed  in  the  defence 
of  dry  ditches,  reveted  with  masonry. 

5th.  Against  the  batteries  of  the  first  parallel  during 
their  erection,  and  after  their  position  has  been  disclosed 
by  means  of  fire-balls. 

6th.  Against  the  head  of  a  sap  at  night. 

7th.  Against  the  workmen  engaged  on  the  construc- 
tion of  the  second  parallel. 

8th.  Against  the  workmen  engaged  on  the  third  par- 


FIRE    OF   THE    SIEGE-HOWITZER.  497 

allel,  against  the  works  leading  to  the  covered  way,  and 
against  the  crowning  of  the  covered  way. 

9th.  Against  craters  formed  by  the  explosion  of 
mines,  to  prevent  the  enemy  from  crowning  them. 

10th.  Against  the  passage  of  the  ditch. 

11th.  Against  the  breach. 

12th.  All  cannon  on  the  flanks  which  remain  mounted, 
fire  rapidly  grape  or  canister  shot  at  the  moment  of 
assault. 

In  the  attach  The  besiegers  are  much  more  restricted 
in  the  use  of  case-shot  than  the  besieged.  It  should  be 
principally  employed  under  the  following  circumstances, 
viz. : 

1st.  By  cannon  placed  on  the  flanks  of  attack  when- 
ever the  besieged  make  a  sortie,  and  come  within  suita- 
ble range. 

2d.  At  night,  against  the  embrasures  which  have 
been  cannonaded  during  the  day  with  solid  shot,  to 
prevent  them  from  being  repaired. 

3d.  Against  the  flanks,  during  the  night. 

4th.  Against  the  breach  during  the  day  or  night,  as 
soon  as  completed,  to  prevent  the  enemy  from  erecting 
means  for  defending  it. 

5th.  Against  the  besieged,  if  he  attempt  to  pass  out 
through  the  breach,  after  the  assault  has  been  repelled. 

479.  Fire  of  the  siege-howitzer.  The  siege-howitzer 
should  be  employed  in  the  defence, — 

1st.  Against  an  attacking  column,  when  the  ground 
in  front  of  the  place  affords  a  shelter  against  the  fire 
of  guns. 

2d.  Against  the  works  of  the  besiegers.  Howitzers 
32 


498  EMPLOYMENT    OF    FIELD-ARTILLERY. 

are  placed  on  the  salients  to  blow  up,  with  shells,  the 
works  situated  on  the  prolongations  of  the  capitals. 

3d.  Against  the  batteries  in  process  of  construction 
on  the  three  parallels. 

4th.  Against  the  heads  of  saps ;  this  fire  should  be 
executed  with  small  charges. 

5th.  The  counter  approaches  are  armed  with  how- 
itzers. 

6th.  Against  troops  opposing  sorties,  and  especially 
against  cavalry. 

7th.  Against  the  enemy's  depots,  when  their  position 
is  known,  and  when  they  are  within  effective  range. 

8th.  Against  the  enemy's  convoys,  when  they  can  be 
reached,  and  they  offer  sufficient  surface. 

In  the  attack.    Howitzers  are  employed  by  besiegers — 

1st.  In  a  bombardment,  by  day  and  night. 

2d.  During  all  periods  of  the  siege,  when  occasion 
requires. 

3d.  In  the  half-parallels  established  between  the 
second  and  third;  against  the  covered- ways  and  places 
of  arms.     The  fire  is  executed  with  small  charges. 

4th.  For  ricochet  fire,  in  preference  to  cannon. 

480.  Use  of  fire-baii§.  Fire-balls  are  used  by  the  de- 
fence— 

1st.  Against  columns  of  attack. 

2d.  Against  the  opening  of  parallels,  so  soon  as  it  is 
ascertained  that  preparations  are  made  for  this  purpose. 

3d.  Against  points  in  the  space  occupied  by  the  be- 
siegers, where  a  remarkable  noise  may  be  heard,  and 
there  is  reason  to  suspect  that  it  proceeds  from  prepa- 
rations for  attack. 

4th.  Particularly  when  it    is  thought  that   the  be- 


FIRE    OF   MORTARS.  499 

siegers  are  about  to  move  forward  from  one  parallel  to 
another. 

5th.  To  discover  the  movements  of  the  enemy  after 
he  has  repulsed  a  sortie,  and  to  prevent  him,  by  the  fire 
of  the  guns  of  the  place,  from  following  too  closely  in 
pursuit. 

In  attack.  As  it  is  for  the  interest  of  the  besiegers  to 
conduct  their  operations  as  silently  and  unobserved  as 
possible,  they  will  seldom  have  occasion  to  use  fire-balls. 

481.  Fire  of  mortars.  Mortars  generally  perform  a 
more  important  part  in  siege  operations  than  howitzers ; 
there  are  times,  even,  when  they  play  a  very  decided 
part ;  too  much  care,  therefore,  cannot  be  employed  to 
render  them  effective. 

In  the  defence.  Mortars  are  employed  in  the  de- 
fence— 

1st.  Concurrently  with  howitzers,  when  the  shape  of 
the  ground  in  front  shelters  the  enemy  from  the  fire 
of  the  guns. 

2d.  Against  batteries  and  heads  of  saps. 

3d.  Against  places  sheltered  from  the  fire  of  flanking 
guns.  Mortars,  and  particularly  light  mortars,  can  be 
suitably  placed  at  all  points,  and  without  interfering 
with  the  establishment  of  gun  and  howitzer  batteries. 

4th.  Against  the  works  of  the  besiegers  generally, 
and  especially  against  the  opening  of  parallels,  and  the 
passage  from  one  parallel  to  another. 

5th.  When  the  besiegers7  fire  has  silenced  the  fire  of 
the  guns,  the  fire  of  the  mortars  continues  in  full  activi- 
ty, not  only  in  the  body  of  the  place,  but  in  the  demi- 
lunes and  lateral  works. 

6th.  In  covered  batteries,  during  the  entire  siege,  but 


500  EMPLOYMENT    OF    FIELD- AETILLERY. 

particularly  during  or  after  the  construction  of  the  third 
parallel. 

7th.  Light  mortars  should  be  employed  in  the  coun- 
ter approaches. 

8th.  Against  the  workmen  who  are  engaged  in  run- 
ning the  sap  up  the  glacis,  for  the  purpose  of  crowning 
the  covered  way. 

9th.  To  prevent  the  construction  of  counter  and 
breaching  batteries. 

10th.  To  prevent  the  besiegers  from  establishing 
themselves  in  the  craters  formed  by  the  mines. 

11th.  To  drive  the  besiegers  from  any  exterior  work 
which  they  have  taken. 

12th.  To  prevent  the  passage  of  the  ditch,  or  render 
it  difficult. 

13th.  To  prevent  the  besiegers  from  effecting  a  lodg- 
ment in  the  breach,  by  firing  from  the  interior  retrench- 
ment. 

In  the  attack.  It  is  very  difficult  to  specify  all  the 
circumstances  which  should  govern  the  besiegers  in  car- 
rying on  a  bombardment,  since  they  depend  on  a  variety 
of  causes ;  the  following,  however,  may  be  enumerated : 

1st.  In  a  regular  attack,  mortars  are  the  first  to  open 
fire,  which  should  be  kept  up  night  and  day  whenever 
a  result  can  be  obtained. 

2d.  Heavy,  and  sometimes  medium-sized,  mortars,  can 
be  employed  to  retard  the  enemy's  works  on  the  front 
of  attack,  the  armament  of  his  batteries,  the  transporta- 
tion of  his  cannon,  and  to  shower  shells  upon  the  places 
where  his  troops  assemble,  and  to  burn  his  principal 
buildings,  etc.  Light  mortars  are  rarely  used  for  these 
purposes,  in  consequence  of  the  distance  of  the  object 


MORTAR    CASE-SHOT.  501 

and  the  lightness  of  the  shells,  which  have  little  force 
of  percussion. 

3d.  Mortars  are  employed  to  throw  shells  over  the 
entire  surface  of  the  ramparts  of  the  front  of  attack ; 
and,  for  this  purpose,  the  fire  should  be  taken  in  the 
direction  of  their  length. 

4th.  They  are  also  employed  against  the  lateral  works 
as  soon  as  the  enemy  seeks  to  establish  his  guns  there 
for  the  purpose  of  retarding  the  works  of  attack. 

5th.  The  curved  or  mortar  fire  of  the  second  parallel 
is  as  efficient  as  that  of  the  first  parallel,  at  all  periods 
of  the  siege.  Light  mortars  here  begin  to  be  usefully 
employed. 

6th.  Light  mortars  are  also  used  with  great  advan- 
tage in  the  half-parallels.  From  this  period  of  the 
siege,  the  covered- way  and  places  of  arms  are  showered 
with  shells. 

7th.  From  the  period  of  the  third  parallel,  the  ene- 
my's flanks  are  plied  with  mortar  shells,  to  support  the 
fire  of  the  counter  batteries. 

8th.  As  soon  as  the  covered-way  is  crowned,  and  sub- 
sequently, when  a  lodgment  in  the  breach  shall  have 
been  effected,  Coehorn  mortars  are  employed  against 
the  enemy,  who  has  withdrawn  to  the  interior  retrench- 
ment of  the  bastion. 

482.  Mortar  case-shot,  &c.  Stones  and  case-shot  from 
mortars,  should  be  thrown  by  the  defence  as  soon  as  the 
besiegers  pass  to  the  construction  of  the  third  parallel, 
and  the  batteries  pertaining  to  it.  This  should  be  con- 
tinued during  the  crowning  of  the  covered-way,  and 
during  the  assault. 

The  besiegers,  on  the  contrary,  employ  these  projec- 


502  EMPLOYMENT    OF    SEA-COAST   ARTILLERY. 

tiles  in  all  the  batteries  of  the  third  parallel,  and,  by 
this  means,  seek  to  drive  the  enemy  from  the  covered- 
way  and  places  of  arms,  thus  preparing  the  way  for  the 
assault. 

EMPLOYMENT  OF  SEA-COAST  CANNON. 

483.  Nature  of.  Artillery  plays  a  very  important 
part  in  sea-coast  defence,  particularly,  since  much  of  it 
is  composed  of  pieces  of  sufficient  power  to  disable  a 
wooden  vessel  by  a  single  well-directed  shot. 

The  principal  advantages  which  sea-coast  cannon  pos- 
sess over  those  mounted  on  ship-board,  arise  from — 

1st.  The  greater  strength  and  stability  of  the  foun- 
dations on  which  they  rest.  Hence  they  are  made  of 
the  largest  calibre,  and  have  perfect  steadiness  of  aim 
in  firing. 

2d.  The  superior  resistance  of  the  covering  materials 
of  land-batteries. 

Hot-shot  and  shells  are  particularly  effective  against 
timber,  but  they  have  very  little  effect  on  earth,  or  good 
masonry. 

3d.  Less  extent  of  vulnerable  surface.  The  vulner- 
able surface  of  a  casemate  battery  comprises  that  of  the 
embrasures ;  that  of  a  barbette  battery  is  composed  of 
those  portions  of  the  guns,  carriages,  and  men  which  are 
seen  above  the  crest  of  the  parapet — forming,  altogether, 
a  narrow  belt,  not  much  exceeding  two  feet  in  width  ; 
whereas,  the  entire  surface  of  a  vessel,  above  the  water- 
line,  is  liable  to  be  seriously  injured  by  projectiles. 

4th.  Superior  height,  or  command  over  the  surface  of 
the  water.  The  crest  of  a  land-battery  is,  at  least,  45 
feet  above  the  surface  of  the  water ;  this  superiority  of 


Of  THE 


UNIVERSITY 


position  gives  not  only  a  greater  range  to  the  artillery, 
but  it  gives  it  a  destructive  plunging  fire  on  the  decks 
of  the  opposing  vessels,  and,  at  the  same  time,  places 
the  battery  beyond  the  reach  of  ricochet  fire. 

5th.  Greater  vertical  and  horizontal  fields  of  fire. 
This  advantage  not  only  gives  greater  range  to  the  pro- 
jectile, but  permits  the  same  number  of  pieces  to  be 
brought  to  bear  on  a  greater  number  of  points. 

484.  Armament.  The  armament  of  sea-coast  bat- 
teries depends  on  their  importance,  and  on  the  depth 
and  width  of  the  channel  to  be  defended. 

The  present  sea-coast  armament  comprises  the  32  and 
42  pounder  guns  for  throwing  solid  shot,  hot-shot,  shells, 
and  case-shot ;  the  8-inch  sea-coast  howitzer  for  throw- 
ing shells  and  case-shot ;  the  8,  10,  and  15-inch  colum- 
biads  for  throwing  shot  and  shells;  and  the  24-pounder 
howitzer  for  throwing  single  or  double  shotted  canister, 
in  the  defence  of  ditches ;  in  addition  to  these,  every 
sea-coast  battery  should  be  provided  with  a  certain  num- 
ber of  field-pieces,  principally  howitzers,  to  prevent  a 
landing,  or  to  act,  in  close  engagements,  against  the  rig- 
ging and  boats  of  vessels. 

Every  battery  should  be  provided  with  permanent 
or  portable  furnaces  for  heating  shot.  One  hour  and 
a  quarter  is  required  to  heat  up  a  furnace  and  bring 
the  shot  to  a  red  heat,  or  half  an  hour  to  heat  the  shot 
if  the  furnace  has  been  previously  heated. 

Hot  shot  are  better  suited  for  protracted  than  for 
short  engagements. 

485.  Fires.  Direct,  ricochet,  and  plunging  fires  are 
principally  employed  in  sea-coast  defence. 

Direct  fire  should  be  used  when  the  surface  of  the 


504  EMPLOYMENT    OF    SEA-COAST   ARTILLERY. 

water  is  rough,  and  the  accuracy  of  the  rebound  cannot 
be  depended  upon.  The  accuracy  of  sea-coast  fire  is 
generally  greater  than  that  of  the  field  or  siege  service, 
for  the  reasons,  that,  the  distance  of  the  object,  though 
moving,  can  be  readily  and  accurately  determined  by 
its  relation  to  known  objects,  the  effect  of  shot  can  be 
more  easily  observed  on  water  than  on  land,  and  the 
size  of  the  object  is  large,  and  its  appearance,  generally, 
well  defined. 

In  aiming  at  a  vessel  with  direct  fire,  the  piece  should 
be  pointed  at  the  water-line ;  for,  if  the  projectile  strike 
the  water,  it  will  either  penetrate  the  hull  below  the 
water-line,  or  rebound  and  strike  above  it. 

The  range  of  effective  direct  fire  does  not  much  exceed 
one  mile  and  a  quarter;  the  extreme  range  of  sea-coast 
mortars  is  about  two  and  a  half  miles ;  that  of  the  co- 
lumbiads,  about  three  and  a  quarter  miles,  and  the  heavy 
rifle-guns  about  five  miles. 

486.  Ricochet-fire.  The  accuracy  of  ricochet -fire 
depends  on  the  surface  of  the  water;  under  favorable 
circumstances,  the  larger  sea-coast  shells  have  a  range  of 
about  3,000  yards  in  rolling  fire ;  their  penetrating  force, 
however,  is  very  much  diminished  toward  the  extrem- 
ity of  this  range. 

The  fire  of  mortars,  from  ship-board,  is  very  uncer- 
tain, if  the  surface  of  the  water  be  much  disturbed. 
This  was  shown  at  the  bombardment  of  Fort  McHenry 
by  the  British,  in  the  War  of  1812,  and  at  the  bom- 
bardment of  San  Juan  d'Ulloa  by  the  French.  In  the 
latter  case,  out  of  302  shells  that  were  fired  at  a  dis- 
tance of  2,200  yards,  six  only  struck  the  fort,  while  others 
fell  1,200  yards  beyond  it. 


r 


TABLE    ONE.  505 


CHAPTER  XIII. 
TABLES  OF  MULTIPLIERS. 

B,  I,  D,   V,  &c. 

487.  Explanation.  It  would  exceed  the  limits  of  this 
work  to  enter  into  a  discussion  of  the  formulas  from 
which  the  values  of  the  multipliers  used  in  the  equa- 
tions of  motion  in  air  (page  412)  are  calculated;  it  will 
be  sufficient  to  explain  how  these  tables  are  used  in 
practice. 

The  pupil  will  find  this  subject,  as  well  as  all  others 
relating  to  Ballistics,  ably  and  fully  treated  in  Didion's 
Traite  de  Balistique. 

488.  Table  1.  Multiplier  B.  The  decimals  are  car- 
ried out  to  three  places,  which  is  sufficient  for  ordinary 

purposes.     The  values  of  —  are  given  in  the  first  hori- 
zontal line,  the  value  of  — '  in  the  first  vertical  col- 

r 

umn,  and  the  values  of  the  corresponding  multipliers 
are  set  opposite  to  them. 

To  find  the  multiplier  B  for  two  intermediate  values 

of--  and  — '   not  given  in  the  tables,  we  seek,  in  the 
c  r 

absence  of  the  proper  numbers,  the  corresponding  values 

of  the  nearest  tabular  numbers.     We  add  to  these,  parts 

proportional  to  the  differences,  as  though  each  part  were 

to  be  considered  separately. 


506  TABLES    OF   MULTIPLIERS. 

x  V 

Example. — Find  the  value  of  B  for  _=0.5755,  and  ——1.1219, 

c  r 

i.  e.  B  (0.5755;  1.1219).     Starting  with   0.55  in  the  first  horizontal 

column,  and  1.10   in  the  first  vertical  column,  we  find  -5=1.479;  the 

difference  between  this  and  the  next  number  of  the  horizontal  line  is 

0.054 ;  the  difference  between  the  same  and  the  next  number  of  the 

vertical  column  is  0.013.     The  difference  between  0.5755  and  0.55  is 

0.0255,    and   between    1.1219    and    1.10    is   0.0219.      The    value  of 

B    (0.5755;     1.1219)=1.479-f Q-02550.054  +0,02190.013  —  1.479  + 
v  J  0.05  0.05 

0.027  +  0.006  =  1.512. 

Or,  for  greater  convenience,  the  foregoing  may  be  placed  in  the  fol- 
lowing form,  the  differences  being  written  as  whole  numbers : 

.#(0.5755;  1.1219)  — 1.512 
^(0.55;  1.10)     =1.479 

s«  • • -  - 

219 

™13    .    .      =        6 
500 


Multiplier,  I.  The  values  of /are  given  in  the  same 
table  as  those  of  JB;  except  that  it  is  necessary  to  com- 
mence in  the  lower  horizontal  line,   and  subtract  from 

V I        V\ 
them  the  product  of  — j  1-) i  J,  by  the  corresponding 

number  of  the  line  called  "  correction." 


Example.— To    find    the   value  of  7(0.5755;    1.1219),    take  -  = 

c 

0.545,  which  is  less  than  the  proposed  number  by  0.305,  and  which 

V 

differs  by  0.035   from  the  next  number  in  the  table;  — '=  1.10  is  the 
*  r 

nearest  number  to  1.1219  in  the  first  vertical  column;  for  these  two 
numbers  we  have  7=1.771.  This  number  differs  from  the  adjoining 
horizontal  and  vertical  numbers  in  the  table  by  0.066  and  0.022,  re- 
spectively.    The  value  sought  is  1.830,  as  is  thus  shown: 


TABLE    FOUK.  507 

7(0.5755;    1.1219)=1.830 

I    (0.545;    1.10)     =1.771 
305 

•66  =      58 


350 
219 

^o522  =     10 

—1.1219.2.1219.4=    —9 

Table  3.    Values  of  U  and  D.     This  table  is  calcula- 

CO 

ted  for  differences  of  0.10  in  case  of  — >  in  the  upper  line, 

C 

and  for  differences  of  .05  in  case  of  — %     For  U,  the 

x 
values  of  -  are  found  in  the  upper  horizontal  line,  and 

c 

for  D,  in  the  lower  line. 

Example.— Find  the  values  of  U  (0.5755  ;  1.1219)  and  D  (0.5755; 
1.1219). 


D  (0.5755;  1.1219)  =  1.336 
D     (0.393;       110)  =  1.221 

1825 

1920119  =   -113 

219 

^005  "  -002 


U  (0.5755;  1.1219)  =  !. 707 
U      (0.50;       1.10)  =  1.597 
755 

Toob138        =  -104 

219       • 

--14  -   .006 

We  have  [7=1.707,  and  Z>  =  1.336. 

Table  4.  Values  of  -  B  for  the  calculation  of  Ranges. 

This  table  skives  the  value  oi-B  for  values  of  -  and  — '-, 
&  G  c  r 

for  differences  of  0.05  and  0.05  ;  the  unknown  quantity 

t  •     x     -         V,       i  <&  T* 
to  be  determined  is  -  wnen  — -  and  -.#=/>,  are  given. 

Arrange  the  calculations  as  in  the  preceding  cases. 
Only  one  of  the  proportional  parts  is  unknown,  and  this 
is  determined  by  the  condition,  that  if  it  be  added  to 
the  other  proportional  part,  and  to  the  number  in  the 
table,  the  sum  is  equal  to  the  required  number. 


508  TABLES  OF  MULTIPLIEES. 

V  x  x 

Examples. — Having  ~  =1.1219  and  -B,  or  ^>=0.8729,  find  -. 

t.'Vk 

Starting  with  —=1.10,  and  following  the  horizontal  line,  we  come 

upon  0.8135,  the  nearest  approach  to  the  proposed  number,  0.8729.    Find 

*  x 

the  corresponding  value  of  —    which  is  0.55;  the  unknown  value  of  — 

surpasses  0.55  by  a  certain  quantity  which  we  shall  call  A ;  following 
the  previous  arrangement  of  the  calculation,  and  observing  that  the 
differences  of  0.8135  with  the  adjacent  horizontal  and  vertical  tabular 
numbers  are  0.1065  and  0.0071,  respectively,  and  representing  by  p  the 
result,  we  have — 

^(0.55  +  A;    1.1219)=0.8720 

/?  (0.55         ;    1.10     )  =  0.8135 

A 

:1065  —   .0559 


0.05 
0.02] 


71  =  .0035 


0.0500 

559 
We  have  A=— — 0.05  =0.0263 

1065 

- =0.55  +  0.0263  =0.5763 

c 

The  proportional  part  559  is  equal  to  8729 — (8135+35Y 

L 

Table  5.      Values  of     r  for  initial  velocities. 

7S 

This  table  gives  the  quotient  arising  from  dividing 

V         x  V 

— ■  by  VB  f°r  values  of  -  and  — - ;  the  quantity  to  be 

.    V 

determined  is   — -.     The  method  is  the  same  as  in  the 
r 

preceding  table  ;  if  the  value  of  the  quotient  q  dimin- 
ishes as  -  increases,  the  sign  of  the  difference  should  be 

G 

changed. 

V, 

Example.— Having  -  =0.5755,  and?=    r    =  0.9110,  find  YL 
c  </B~  r  ' 


TABLES.  %       509 

x 
The  vertical  column  nearest  to  -=0.5755  is  that  which  corresponds 

to  0.55  ;  the  number  in  this  column  nearest  to  0.9110  is  0.9045,  which 
corresponds  to  1.10,  and  the  difference  between  this  and  the  required 
number  is  0.0065  ;  the  differences  with  the  neighboring  numbers  to  the 
right  and  above,  are  —  0.0162  and  0.0370,  respectively.  We  therefore 
have, 

#(0.5755;  1.10+A)  =  0.9110 


q  (0.55;  1.10)  =0.9045 

147 
or  A=— -0.05  =0.0199 

V 

and  —^=1.10+0.0199  =  1.1199 

r 

The   proportional  part  147    is  equal  to  9110 — (9045 — 82),  giving 

V 

A  =  0.0199,  which,  added  to   1.10  gives  — '=1.1199. 


510  TABLES. 

Table  1. — Values  of  B  and  L 


,1  - 

B      |     c 

0.00 

0.05 

0.10 

0.15 

0.20 

0.25 

0.80 

0.85 

0.40 

0.45 

0.50 

0.00 

1.000 

1.017 

1 .034 

1.052 

1.070 

1.089 

1.10* 

1.128 

1.148 

1.169 

1.190 

0.05 

1.000 

1.018 

1.036 

1.055 

1.074 

1 .098 

1.114 

1.134 

1.156 

1.177 

1.200 

0.10 

1.000 

1.019 

1.038 

1.057 

1.077 

1.098 

1.119 

1.141 

1.163 

1.1-6 

1.210 

0.15 

1.000 

1.020 

1.039 

1.060 

1.081 

1.103 

1.125 

1.148 

1.171 

1.195 

1 .220 

0.20 

1.000 

1.020 

1.041 

1.063 

1.085 

1.107 

1.130 

1.154 

1.179 

1.205 

1.231 

0.25 

1.000 

1.021 

1.043 

1.065 

1.088 

1.112 

1.136 

1.161 

1.1871  1-21' 

1.241 

0.80 

1.000 

1.022 

1.045 

1.068 

1.0^2 

1.117 

1.142 

1.168 

1.195 

1.223 

1 .252 

0.8* 

1.000 

1.023 

1.046 

1.071 

1.096 

1.121 

1.148 

1.175 

1.203 

1.282 

1.262 

0.40 

1.000 

1.024 

1.048 

1.078 

1.099 

1.126 

1.1*8 

1.182 

1.2H 

1.241 

1.273 

0.45 

1.000 

1.025 

l.o.-.o 

1.076 

1.108 

1.181 

1.159 

1.189 

1.219 

1.251 

1.288 

0.50 

1.000 

1.025 

1.058 

1.0. 9 

1.107 

1.185 

1.165 

1.196 

1.227 

1 .260 

1.294 

0.55 

1.000 

1.026 

1.058 

1.0*2 

1.110 

1.140 

1.171 

1.203 

1.235 

1.269 

1.805 

U'l  . 

0.60 

1.000 

1.027 

1.055 

1  084 

1.114 

1.146 

1.176 

1.209 

1.244 

1.2.9 

1.315 

th- 

0.C5 

1 .000 

1.028 

1.057 

1  C87 

1.118 

1.149 

1.182 

1 .216 

1.25* 

1.288 

1.826 

I 

0.70 

1 .000 

1.029 

1.059 

1.090 

1.122 

1.1M 

1.188 

1.224 

1.260 

1.298 

1.887 

0.75 

1.000 

1.080 

1.060 

1.092 

1.125 

1.159 

1.194 

1.281 

1.268 

1.30S 

1.348 

£ 

0.80 

1 .000 

1.031 

1.062 

1  095 

1.129 

1.164 

1.200 

1.23S 

1.277 

1.817 

1.859 

0.85 

1.000 

1 .031 

1.064 

1.098 

1.133 

1.169 

1.206 

1.V45 

1.285 

1.827 

1.870 

0  90 

1.000 

1 .082 

1.066 

1.101 

1.137 

1.173 

1.212 

1.252 

l.kM 

1.387 

1.3S2 

0.95 

1.000 

1.038 

1.067 

1.108 

1.140 

1.178 

121- 

1.259 

1.302 

1.846    1.893 

1.00 

1.000 

1.034 

1.069 

1.106 

1.144 

1.183 

1.221 

1.266 

1.310 

1.356 

1.404 

1.05 

1.000 

1.035 

1.071 

1.109 

1.148 

1.188 

1.230 

1  273 

1.319 

1.366 

1.415 

1.10 

1  000 

1.086 

1.073 

1.112 

1.151 

1.198 

1.236 

1.2-1 

1.32S 

1.376 

1.427 

1.15 

1.000 

1.037 

1.075 

1.114 

1.155 

1.198 

1 .242 

1.2S> 

1.836 

1  386 

1 .488 

1.9  • 

1.000 

1.087 

1.076 

1.117 

1.159 

1 .203 

1.24S 

1.295 

1 .345 

1.396 

1.450 

. 

1.25 

1.000 

1.038 

1.078 

1.120 

1.163 

1.207 

1.254 

1 .303 

1.353 

1.406 

1.461 

For     1     a? 

7      1     7 

0.000 

0.033 

0.067 

0.101 

0.134 

0.168 

0.202 

0.236 

0.270 

0.804:  0.388 
0.001J  0.001 

1 
rorrtction 

0.000 

0.000 

0.000 

0.000 

0.000 

0.000 

0.000 

0.001 

0.001 

Fo- 
B 

■ 

0 

0.50 

0.55 

0.60  j  0.65 

0.70 

0.75 

0.80 

0.85 

0.90 

0.95 

1.00 

I  0.00 

1.190 

1.212 

1.234 

1.257 

1.2*1 

1.805 

1 .330 

1.855 

1.882 

1 .409 

1 .487 

0.05 

1.200 

1.223 

1.V47 

1.271 

1.296 

1 .322 

1.84S 

1.875 

1.40 

1.43' 

1.461 

0.10 

1.210 

1.284 

1.259    1.285 

1.81' 

l.«89 

1.866 

1 .395 

1 .425 

1 .455 

1.486 

0.15 

1.220 

1.246 

1.272!  1/99 

1.827 

1.85« 

1.885 

1.415 

1.447 

1.479 

1.512 

0.20 

1  .-281 

1 .25S 

1.2-5    1.814 

1.348 

1  .378 

1.404 

1.436 

1.469 

1.503 

l.ftw 

0.25 

1.241 

1.269 

1.298!   1.828 

1 .359 

1 .3!i0 

1.428 

1.457 

1.491 

1.6*1 

1.563 

0.80 

1.252 

1.281 

1.811     1.348 

1 .875 

1.408 

1.442 

1.477 

1.514 

1.551 

1.590 

0.85 

1.262 

1.293 

1.8.-5    1.357 

1 .391 

1.425 

1.461 

1.499 

1.586 

1.5  6 

1  616 

0.40 

1.278 

1.805 

1.833    1.872 

1 .407 

1.448 

1.48 

1.520 

1.559 

1.601 

1.643 

0.45 

1.2-3 

1.317 

l.*51    1.8-7 

1.428 

1.461 

1.500 

1.541 

1 .5S8 

1.626 

1.610 

0.50 

1.294 

1.829 

1.365    1.402 

1.440 

1.479 

1.520 

i  .563 

l.fOt 

1.651 

1.697 

^k 

,•0.55 

1 .805 

1.841 

1.878    1.417 

1 .457 

1.498 

1.540 

1.584 

1  630 

1.677 

1.725 

a  1 

0.60 

1.815 

1 .353 

1.8921   1.432 

1 .473 

1.516 

1 .560 

l.i-OB 

1.654 

1.70 

1.753 

u 

0.65 

1 .826 

1 .865 

1.406    1.447 

1.490 

1.585 

1.581 

1.629 

1.678 

1.729 

1.781 

o 

0.70 

1 .387 

1.378 

1.4201  1.468 

1.507 

1  553 

1.601 

1.651 

1.70; 

1.755 

1.810 

0.75 

1.34- 

1.  90 

1.433|  1.478 

1.524 

1.572 

1.622 

1.674 

1.7*7 

1.7-2 

1.839 

0.80 

1.859 

1.403 

1.4471  1.494 

1.542 

1.591 

1.643 

1.696 

1.751 

1.809 

1.868 

0.85 

1.870 

1.415 

1.462 

1.509 

1.559 

1.610 

1.664 

1.719 

1.776 

1  >30 

1.897 

0  90 

1.88 

1 .428 

1.476 

1.525 

1.577 

1   630 

1  6-5 

1.748 

1.802 

1.86< 

1.927 

0.95 

1.898 

1.440 

1 .490 

1.541 

1.594 

1.649 

1.706 

1.766 

1.8*1 

1.691 

1.957 

1.00 

1.404 

1 .453 

1.504 

1.557 

1.6'2 

1.669 

1.728 

1.7S9 

1.853 

1.919 

1.9-7 

1.05 

1 .415 

1.466 

1 .5.9 

1 .574 

1.630 

1.6S8 

1.749 

1.813 

1.879 

1.941 

2.017 

'   1.10 

1.427 

1.479 

1.5=8 

1.590 

1.64H 

1.708 

1.771 

1.881 

1.905 

1.975 

2.048 

1.15 

1.488 

1.49^ 

1.548 

1.606 

1.666 

1.728 

1.798 

1.R61 

1.981 

9.004 

2  079 

1.20 

1.450 

1  505 

1.563 

1.623 

1.684 

1.749 

1.816 

1 .8S6 

1.958 

8.088 

¥.111 

1.25 

1.461 

1.5IS 

1  578 

1 .639 

1.703 

1.769 

1.838 

1.910 

l.s-65 

2.06.' 

2.142 

For 

0) 

c 

0.83s 

0.372 

0  407 

0.441 

0.476 

0.511 

0.545 

0.5S0 

0.615 

0.650 

0.685 

Correct 

on 

0.001 

0.002 

0.002 

0.002 

0.003 

0.003 

0.004 

0.004 

0.005 

0.005 

0.006 

TABLES. 


511 


Values  of  B  and  I. — (Continued?) 


For 
B 

1.00 

!  1.05 

1.10 

1.15 

1.20 

|  1.25 

1.80      1.85  J  1.40 

! 

l 
1.45  !  1.50 

r  o.oo 

1.437 

1.465 

1.494 

1.525 

1.556 

1.588    1 .621 1  1.654 

1.689 

1.725:  1.762 

0.05 

1.461 

1.492 

1.523 

1.555 

1  1.588 

1.6221  1.657    1.698 

1.730    1.768!  1.808 

0.10 

1.486 

1.519 

1.552 

;  1.586 

!  1.621 

1.657|  1.6941  1.782 

1.772 

1.812!  1.854 

0.15 

1.512 

1.546 

1.581 

1  1.620 

|  1.654 

1.6921  1.782!  1.772 

1.814 

1.857    1.902 

0.20 

1.53S 

1.573 

1.610 

1.649 

'  1.688 

1.T2S   1.770!  1.818 

1.857 

1.908    1950 

0.25 

1.56* 

1.601 

1.610 

1.681 

1.722 

1  1.765    1.809|  1.854 

1.901 

1.949!  1.999 

0.80 

1.5  0 

1.629 

1.670 

1.713 

1.757 

1 .802 

1.848    1.896 

1.945 

1.996 

2.049 

0.35 

1.M6 

1.658 

1.701 

1.746 

1.792 

1.889 

1.888    1.988 

1.990 

2.044 

2.100 

0.40 

1.643 

1.6»7 

1.732 

1.779 

1.827 

1.877 

1.928    1.981 

2.036 

[  2.098 

2.151 

0.45 

1.670 

1.716 

1.763 

1.812 

1.868 

1 .915 

1.969;  2.025 

2.083 

1  2.142 

2.203 

„. 

0.50 

1.'97 

1.745 

1.795 

1.846 

1  899 

1.954 

2.01l!  2.069 

2.129 

2.192    2.256 

M* 

0.55 

1.725 

1.775!  1.827 

1.881 

1.936 

1.998 

2.0  3    2.114 

2.177 

2.242J  2.810 

e  1 

0.60 

1.7.-3 

1.805    1.859 

1.915 

1.973 

2.033 

2.095    2.159 

2.225 

2.293!  2.364 

J- 

0.65 

1.781 

1.836    1.682 

1.950 

2.011 

2.073 

2.138!  2.205 

2.274 

2.345!  2.419 

1 

0.70 

1.810 

1.866!  1.925 

1.986 

2.049 

2.114 

2.182:  2.251 

2.323 

2.398    2.475 

0.75 

1.899 

1.8971  1.958 

2.022 

2.085 

2.155 

2.226    2.29S 

2.373 

2.451 

2.582 

0.-0 

1.868 

1.929;  1.99; 

2.058 

2.12^ 

2.197 

2.270!  2.846 

2.424 

2.505 

2.589 

0.85 

1.897 

1.9  0!  2.026 

2.095 

2.166 

2.239 

2.315^  2.394 

2.475 

2.560 

2.648 

0.90 

1 .927 

[.992    2.061 

2.132 

2.206 

2.2821  2.361!  2.448 

2.527 

2.616 

2.707 

0.95 

1.957 

2.1(25    2.096 

2.169 

2.246 

2.325 

2.407    2.492 

2.580 

2.672 

2.766 

1.00 

1.987 

2.057|  2.131 

2.207 

2.287 

2.369 

2.454!  2.542 

2.633 

2.726 

2.627 

1.05 

2.017 

2.090    2.167 

2.246 

2.32S 

2.413 

2.501]  2.593 

2.687 

2.786 

2.688 

1.10 

2. 046 

2.127 

2.203 

2.284 

2.370 

2.458 

2.549!  2.644 

2.742 

2.844 

2.950 

1.15 

2.079 

2.157 

2.240 

2.323 

2.412 

2.503 

2.5971  2.695 

2.797 

2.903 

3.018 

1.20 

2.111 

2.191 

2.276 

2.863 

2.454 

2.548 

2  646;  2.746 

2.853 

2.963 

8.076 

1.25 

2.142 

2.225 

2.313 

2.403 

2.49: 

2.594 

2.696!  2.801 

2.909 

3.028 

8.141 

For 
I 

X 

c 

0.685 

0.721 

0.756 

0.791 

0.827 

0.863 

0.899    0.934 

0.970 

1.006 

1.043 

Correcti 

r>n     ... 

0.006 

0.007 

0.007 

0.00* 

0.009 

0.010 

0.011!  0.015 

0.013 

0.014 

0.015 

For 
B 

X 

c 

1.50      1.55 

1.60 

1.65 

1.70 

1.75 

1.80 

1.85 

1.90 

1 
1.95     2.00 

0.00 

1.762    1.799 

1.838 

1.878 

1.920 

1.962 

2.00'.  1  2.051 

2.097 

2.145!  2.194 

0.05 

t.80"    1.848 

1.890 

1.988 

1.977 

2.022 

2.069    2.117 

2.167 

2.218!  2.271 

0.10 

1.654    1.897 

1.942 

1.98- 

2.035 

2.0v 

2.i:-8 

2.165 

2.23> 

2.293!  2.5-49 

0.15 

1.902    1.94- 

1.995 

2.044 

2.094 

2.145 

2.199 

2.254 

2."10j  2.*69|  2.429 

0.20 

1.950    1.999 

2.049 

2.101 

2.154 

2.209 

2.265 

2.*24 

2.384    2.44i>!  2.511 

0.25 

1.999    2.051 

2.104 

2.158 

2.215 

2.27« 

2.833 

2.395 

2.459 

2.525,  2..' 94 

0.30 

2.049    2.103 

2.159 

2.217 

2.277 

2.899 

2.402 

2.468 

2.536 

2. '06   2. 676 

0.85 

2.100    2.157 

2.216 

2.277 

2.840 

2.405 

2.473 

2.542 

2.614 

2.688    2.7»5 

0.40 

2.151    2.211 

2.274 

2.339 

2.405 

2.473 

2.544 

2.617 

2.693 

2.771;  2.652 

0.45 

2.203    2.267 

2.8  2 

2.400 

2.470 

2.542 

2.*17 

2.694 

2.774 

2.857!  2.942 

^U 

0.50 

2.256    2.328 

2.391 

2. 463 

2.536 

2.«lv 

2.691 

2.772 

2., -56 

2.9481  3.083 

0.55 

2.310;  2.3-0 

2.452 

2.526' 

2.604 

2.6*3 

2.766 

2.851 

2.940 

8.081!  8.126 

e  1 

0.60 

2.:  64    2.437 

2.518 

2.i 591 

2.672 

2.75' 

2.842 

2.932 

3.025 

8.121!  3.220 

«- 

0.65 

2.419    2.4'6 

2.575 

2.657 

2.742 

2.629 

2.920 

3.014 

8.111 

x.212    3.816 

o 

0.70 

2.475    2.555 

2.f38 

2.723 

2.812 

2.904 

2.999!  8.097 

3.199 

8.804    8.413 

0.75 

2.682    2.615 

2.702 

2.791 

2.8-4 

2.979 

*. 079    8.181 

8.288 

3.398    6.512 

0>0 

2.589    2.676 

2.7'6 

2.860 

2.956 

3.056 

8.160 

8.267 

8.379 

3.494    3.613 

0.85 

2. 64S|  2.738 

2.832 

2.929 

8.080 

3.134 

3.242 

8.:54 

8.471 

8.591;  8.715 

0.90 

2.707    2.801 

2>98 

8.000 

8.105 

3.218 

8.826 

8.443 

8.564 

3.689!  8.819 

0.95 

2.766J  2  864 

2.966 

3.07l| 

3.180 

8.2«'8 

8.411 

8.582 

8.659 

3.790'  3.925 

1.00 

2.627    2.928 

3.034 

8.144 

3.257 

8.875 

8.497 

8.623 

8.755 

8.891 

4.082 

1.05 

2.88-1  2.998 

H.103 

8.217 

8>85 

3.457 

8.584 

8.716 

8.652 

8.994 

4.141 

1.10 

2.950    8.059 

8.173 

8.291 

8.414 

8.541 

*.fi73 

3.809 

3.951 

4.099 

4.251 

1.15 

8.013:  3.126 

3.244 

8.8<;7 

8.494 

8. '25 

8.762 

3.904 

4.052 

4.205 

4.P63 

1.20 

8.076:  3.194 

8.816 

8.443 

8.575 

8.711 

3.858 

4.000 

4.158 

4.812 

4.477 

. 

1.25 

3.141    3.262 

3.389 
1.115 

3.520J 

8.657 

8.798 

8.945 

4.098 

4.257 

4.421 

4.592 

1  or 

1 

1     x 
1     « 

| 
1.048    1.079 

1.151 

1.188 

1.225 

1.261 

1.298 

1.385 

1.372 

1.409 

Correcti 

• 

on 

0.015    0.017 

0.018 

0.019 

0.021 

0.022 

0.024J  0.025!  0.027 

0.029!  0.081 

512 


TABLES. 


Table  3. — Values  of  U  for  velocities  and  D  for 

times. 


For 
U 

X 

e 

j  0.00 

0.10 

0.20 

0.30  :  0.40 

0.50  !  0.60 

:  0.70 

0.80   !  0.90 

1.00 

0.00 

1.000 

1.051 

1.105 

1.188   1.221 

1.884    1.850 

1.41S 

1.4' 2    1.568 

1.649 

0.05 

1.000 

1.054 

1.110 

1.170    1.238 

1.298    1.867 

1.44C 

1.516    1  597 

1.6S1 

0.10 

1.000 

1 .056 

1.116!  1.178'  1.244 

1.312    1.88B 

1.461 

1.641    1.625    1.714 

0.15 

1.000 

1.068 

1 .121 1  1.1861  1.255    l.:-27i  1.402 

1  ASi 

1.566!  1.654    1.746 

0.20 

1.000 

1.062 

1.1261  1.194    1.2' 6    1.341    1.481 

1  509 

1.590!  1.682    1.779 

0.25 

1.000 

LOW 

1.132    1.202!  1.277 

1.865    1.4:37 

1  524 

1.61C 

1.71! 

1.811 

0.30 

1.000 

1.007 

1.1*7. 

1.210.  1.88") 

l.xeO,  1.455]   1  64E 

l.<39 

1.7  1 

1.843 

0.85 

1.000 

1.069 

1.142 

1.219    1.2'.<9 

1.3S3!  J  .472    1  564 

1.664 

1.767 

1.876 

0.40 

1.000 

1.072 

1.147 

1.227,   1.810 

l.»98|  1.490 

1.58. 

1.689 

1 ,79i 

1.90S 

0.45 

1.000 

1.074 

1.153 

1.285!  1.821 

1.412    1.507 

1.608 

1.718 

1.824 

1.941 

H- 

0.50 

1.001) 

1.077 

1.158 

1.248    1.889    1.426!  1.525 

1.629 

1.738 

1.858    1.973 

0.55 

1.000 

1.080 

1.163 

1 .251)  1.848    1.4401  1.542 

1.650 

1 .7*9 

1. 881    2.006 

a  1 

0.60 

1.000 

1.0S2 

1.168 

1.269    1.354;  1.454    1.5*0 

1.'71 

1.787 

1.909    2.088 

1 

0.65 

1.000 

1.035 

1.174 

1.867    1.865    1.469    1.577 

1.6  2 

1.612 

l.«8S    2.070 

0.70 

1.000 

1.0S7 

1.179 

1.876    1.376   1.488    1.596 

1.712 

1.836 

1.966    2.103 

0.75 

1.000 

1.0' 0 

1.184 

1.288!  1.388!   1.497    1.618 

1.7-3 

L.S6J 

1.995    2.185 

0.80 

1.000 

1.092 

1.189 

1 .291i  1 ,899j  1.511    1.680 

1 .  7M 

1.886 

2.028    2.1 68 

0.85 

1.000 

1.090 

1.196 

1.2991  1.410!  1.525    1.647 

1.775 

l.'lO 

2.051    2.200 

0.90 

1.000 

1.097 

1.200 

1.808    1.421!  1.540    1.666 

1.796 

2.080    2.283 

0.95 

1.000 

1.100 

1.205!  1.P16I  1.432|  1.554    1.682 
1.210    1.824!  1.443!  1.583!  1.700 

1.817 

1 .969 

2.  His    2.265 

1.00 

1.000 

1.103 

1/8S 

1.984 

2.187    2.29T 

1.05 

1.000 

1.105 

1.216    1.882    L.464 

1.662    1.717 

1.859 

2.00S 

2.165    2.'80 

1.10 

1.000 

1.108 

1.221!  1.340    1.468 

1.591    1.785 

1.880 

2.088 

2.194 

2.862 

1.15 

1.000 

1.110 

1.226'  1.34s    1.4T6 

1.611 

1.752 

1.901 

2.067 

2.222 

2.8H5 

1.20 

1.000 

1 .113 

1.281 

1.868    1.487 

1.625 

1.770 

1.922 

2.0S2 

2.250 

2.427 

1.25 

1.000 

1.115 

1.237 

1.864   1.498 

1.629 

1.787 

1.948 

2.107 

2.279 

2.460 

For 

X 

2> 

c 

0.000 

0.198 

0.398 

0.5S5 

0.775 

0.962 

1.146 

1.827 

1.506 

1.6S3 

1.858 

For 
U 

X 

c 

1.00 

1.10 

1.20 

1.30 

1.40 

1.50 

1.60 

1.70 

1.80  1  1.90 

2.00  ' 

< 

0.00 

1.649 

1.7*3 

1.822    1.916    2.014'  2.117 

2.226!  2.340 

2.460   2.586    2.718 

0.05 

1.681 

1.770 

1.888   1.961    2.064    2.173 

2.287!  2.407 

2.533!  2  665    2.804 

0.10 

1.714 

1  807 

1.904!  2.007    2.115    2.229 

2.348!  2.474 

2.606!  2.744    2  890 

0.15 

1.746 

1.S43 

1.945J  2.053    2.166;  2.2.85    2.409!  2.541 

2.679    2.S24    2.976 

0.20 

1.779 

1.880 

1.987    2.099    2.217J  2.840    2.471 1  2.608 

2.752    2.908    8.068 

0.25 

1.811 

1  917 

2.028|  2.144    2.267!  2.896 

2.582    2.675 

2.825   2.982    3.148 

0.*0 

1.843 

1.958 

2.069!  2.190    2.31S    8.451 

2.593    2.742 

2  S98   8.061    8.284 

0.35 

1,876 

1.990 

'2.110    2.236    2.369,  2.508 

2.655    2.809 

2  971    3.141 !  3.320 

0.40 

1.90S 

2.027! 

2.15l!  2.282    2.419    2.564 

2.716|  2.876 

8.048   8.220   3.406 

0.45 

1.941 

2.063! 

2.192;  2.328    2.470    2.620 

2.777    2  943 

8.1161  8.299,  3.492 

^ . 

0.50 

1.973 

2.100 

2.233;  2.373!  2.5*11  2.676 

2.838    8.010 

8.189    3.379,  3.577 

M* 

0.55 

2.006 

2.187 

2.274 

2.419    2.571;  2.731 

2.800   3.077 

8.262   8.458   3.663 

3   1 

0.60 

2.038 

2.173 

2.315 

2.465    2.622!  2.787 

2.961    3.143 

3.385!  3.537|  3.749 

fe 

0.65 

2.070 

2.210| 

2.357 

2.511    2.673'  2.848    3.022!  3.210 

3.40SJ  8.616    8.886 

1 

0.70 

2.108 

2  247! 

2.398 

2.556    2.723    2.899    8.0*8.  8.877 

3.481    3.696    3  921 

0.75 

2.135 

2.283 

2.439;  2.602    2.774'  2.955 

8.145!  3.344 

8  554    8.775   4.007 

0.80 

2.168 

2.3201 

2.480 

2.648    8.825   3.011 

3.206    3.411 

8.627    8.854   4.093 

0.85 

2.200 

2.357 

2.521 

2.694;  2.875    3.066 

8.267!  3. 478 

8.700   8.933    4.179 

0.90 

2.233 

2.393 

2.562 

2.740    2.926   3.122 

3.8291  3.545 

8.778   4.013 

4.265 

0.95 

2.265 

2.430! 

2.603 

8.786    2.977    3.178 

8.890   3.612 

3. 846   4.092 

4.351 

1.00 

2.297 

2.467: 

2.644 

2.831    3.028    3.234 

3.451    3.679 

8.919    4.171 

4.437 

1.05 

2.380 

2  503 

2.686 

2.677    3.078    3.290i  8.512    3.746 

3.992'  4.251    4.588 

1.10 

2.862 

2.540 

2  726 

2.988    3.129    3.346!  3.574   3.813 

4.065   4.330;  4.608 

1.15 

2.395 

2  577 

2.768 

2. 968    3.180    3.4021  3.635   3.8S0 

4.1:J8'  4.409|  4.694 

1.20 

2.427 

2.613 

2.809 

3.014    8.230    3.4571  3.696   3.947 

4.2111  4.4^9,  4.780 

. 

1.25 

2.460 

2.660 

2>50 

3.060j  3.281;  3.513|  8.75S    4.014 

4.284   4.568!  4.866 

r  or 
D 

X 

c 

1.886 

i 
2.080 

2.199 

i          I         ! 

2.369    2.535    2.701    2.864   3.026 

1                                     1 

3.186    3.344;  8.501 

TABLES. 


513 


Table  4. — Values  of  -B  for  ranges. 


z.    I  0.00 

c      ! 


0.00 
0.05 
0.10 
0.15 
0.20 
0.25 
0.30 
0.35 
0.40 
0.45 
0.50 
0.55 
0.60 
0.65 
0.70 
0.75 
0.80 
0.85 
0.90 
0.95 
1.00 
1.05 
1.10 
1.15 
1.20 
1.25 


0.05 


0.10 


0.15 


0.000  0 
0.000  0 
0.000  0 
0.000  0 
0.000  0 
0.000  0 
0.0000 
0.000  0 
0.000  0 
0.000  0 
0.000  0 
0.000  0 
0.000  0 
0.000  0 
0.000  0 
0.000  0 
0.000  0 
0.000  0 
0.000  0 
0.000  0 
0.000  0 
0.000  0 
0.000  0 
0.000  0 
0.000  0 
0.000  0 


0508  0 

0509  0 
.0509  0. 
.0510  0. 
.05100. 
.05110. 
.0511  0. 
.0511  0. 
.0512  0 
.0512  0. 
.0513  0. 
.0513  0. 
.05140. 
.0514  0. 
.0514  0. 
.0515  0. 
.0515  0. 
.0516  0. 
.0516  0. 
.0517  0. 
.0517  0. 
.0517  0. 
.0518  0. 
.0518  0. 
.0519  0. 
.0519  0. 


1034  0. 
1036  0. 

1038  0. 

1039  0. 
1041  0. 
1043  0. 
10450. 
1046  0. 
1048  0. 
1050  0. 

1052  0. 

1053  0. 
1055  0. 
1057  0. 

1059  0. 

1060  0. 
10620. 
1064  0. 

1066  0. 

1067  0. 
1069  0. 
1071  0. 
1073  0. 

1075  0. 

1076  0. 
1078  0. 


0.25 


1578  0. 
15S2  0. 
1586  0. 
1590  0. 
1594  0. 
1598  0. 
1602  0. 
1006  0. 
1610  0. 
1614  0. 
1018  0. 
1622  0. 
1626  0. 
1630,0. 
1634  0. 
16380. 
16430. 
1647  0. 
1651  0. 
1655  0. 
1659  0. 
1663  0. 
1667  0. 
1671  0. 
1676  0. 
16S0  0. 


2140  0 
2148  !0 
2155  !0 

2162  0 
21690 
2177J0 
2184j0 
2191:0 
2199  0 
220610 
2213  0 
2221  0 
2228  JO. 
2286  0 
2243  0 


0.35 


0.40 


2250 

2258 

2265 

2273 

2280 

2288 

2295  0 

2303  0 

231010 

231810 

232610 


2722  0 
2784  0 
2745  0 
2757  0 
2768 10 
278010 
2791  0 
2803  ;0 
2815,0 
282610 
233S0 
2850,0 
2862  0 
287410 
2886!  0, 
2897 !0 
2909 ;0, 
29910, 
2933  0 
29460, 
2958|0. 
2970  0. 
29S2.0. 
299410. 
3006!  0. 
301910. 


3324  0 
33410 
3357  0 
3374  0 
3391  0 
3408  0 
3425  0 
3443  0 
3460  0 
3477  0 
3494  0 
3512  0 
3529  0 
3547  0 
3564  0 
808210 
3600  0, 
36170 
3635  0. 
3653  0. 
36710, 
86890. 
3707  0. 
3725  0, 
3743  0, 
3761,0, 


3947  0 
8970  0 
3993  0 
40170 
4040  0 
4064  0 
4088  0 
4112  0 
4136  0 
41600 
41840 
4209  0 
4233  0 
4257  0 
4282  0 
4307  0 
4332  0, 
4356  0 
4381  0. 
4407  0, 
4432  0. 
4457  0, 
4482  0, 
4508  0. 
4533  0, 
4559  0, 


0.45 


4591  0 
4622  0 
4654.0 
4685  0 
47160 
4748  0 
4780  0 
4812  0. 
48440. 
4877  ;0. 
4909  0. 
4942  0, 
4974  0. 
5007  !0. 
5040  0. 
5074  0. 
5107  0. 
5140,0. 
5174  0. 
5208  0. 
5242  0. 
5276  0. 
53100. 
5344  0. 
5379  0. 
5414|0. 


0.50 


5258  0. 
0. 
9  0. 
.5379:0. 
.54200. 
.5461  0. 
.55030. 
.5544J0. 
.558610. 
.56280. 
.567010. 
.57120. 
.575510. 
.57970. 
.584110. 
.5S84|0. 
.5927J0. 
.5971;0. 

.6015:0. 

.60590. 
.6103  0. 
.6147  0. 
.61920. 
.62370. 
62S2  0. 
6327J0. 


5949 
6000 
6051 
6102 
6154 
6206 
6258 


6416 
6470 
6523 
6577 
6682 
6686 
6741 


7020 
7076 
7133 
7191 

7248 


33 


514 


TABLES. 


Table  5.- 


V 


-Values  of    r 
B 


for  initial  velocities. 


0.00  I  0.05 


0.10  |  0.15  I  0.2J     0.25 


0.80 


0.35 


0.40 


0.45 


0.50 


0.05 
0.10 
0.15 
0.20 
0.25 
0.80 
0.85 
0.40 
0.45 
0.50 
0.55 
0.60 
0.65 
0.70 
0  75 
0.80 
0  85 
0.90 
0.95 
1.00 
1.05 
1.10 
1.15 
1.20 
1.25 


0.0000 
0.0000 
0.0000 
0.0000 
0.0000 
0.0000' 
0.0000 
0.0000 
0.0000 
ii. iii  mo 
0.0000 
0.0000, 
0.0000 
0.0000 
0.0000 
0.0000 
0.0000 
0.0000 
(t. Ill  II 10 

0.0000 
0.0000 
0.0000 
0.0000 
0.0000 
0.0000 


0. 

.04956 

.09908 

.14857 

.19800 

.24739 

.29675 

0.3461 

0.3953 

0.4446 

0.4933 

0.5429 

0.5920 

0.6411 

0.6901 

0.7391 

0.78S0 

0.8370 

0.8857 

0.9347 

0.9884 

1.0322 

1.0809 

1.1295 

1.1781 

1.2267 


0. 

.04913 

.09816 

.14713 

.19601 

.24430 

.29351 

0.3422 

0.3907 

0.4392 

0.4876 

0.08SI 

0.5841 

0.6323 

0.6803 

0.7283 

0.7762 

0.8241 

0.8717 

0.9195 

0.9671 

1.0145 

1.0620 

1.1094 

1.1566 

1.2033 


0. 

.04869 
.09725 
.14569 
.19402 
.24221 
.29029 
0.8888 
0.3361 
0.4333 
0.4815 
0.5289 
0.5762 
0.8988 
0.6706 
0.7176 
•  .7645 
0.8113 
0.8579 
0.9045 
O.9509 
0.9971 
1.0434 
1.0395 
1.1354 
1.1813 


0. 
.04825 


.14426 
.19204 
.98968 
.28710 
0.3344 
0.3315 
'.4235 
0.4754 
0.5220 
0.5635 
0.6148J 
0.6610 
0.7071! 
0.753" 
0.7937 
0.S443 
0.8397 
'•.9349 
0.9801 
1.0251 
1.0700 
1.1146 
1.1592 


0. 

.04782 

.09543 

.14284 

.19')"7 

.23703 

.23392 

o.33o6 

0.3770 

0.4232 

0.4693 

0.5152 

0.5608; 

0.6063 

0.6516 

0.6967 

0.7416 

0.7363 

0.8309 

0.8752 

0.9194 

0.9634 

1.0072 

I.11SO8 

1.0942 

1.1375 


i. 04738  .04695 
.09452  .09362 
.14143  .14001 
.18311  .13614 
.23454  .98900 
23075  .27759 
0.8987  .3229 
0.3725  0.3650 
0.4180  0.4198 
0.4633  0.4573 
0.5084  0.5016 
0.5532  J  0.5456 
0.5978  0.5894 
0.6422  1.6329 
0.6864  0.6761 
0.7303  0.7191 
0.7741  0.7619 
0.8176  0.8044 
0.8609  jo. 8467 
0.9U40  0.8887 
0.9469  0.9305 
0.9895  0.9720 
1. 0881  >  II. 0184 i 
1.0741  1.0543 
1.1162  1.1952 


0. 

.04651 
.09271 
.13860 
.13418 
.99949 
.27444 
0.3191 
0.8035 
0.4O75 
.4513 
0.4948 
'.5380 
1.6810 
0.6236 
0.6659 
0.7080 
.7498 
0.7913 
0.8327 
0.8780 
0.9148 
0.9547 
0.9!  149 
1.0848 
1.0745 


.04564 
,'9<91 
.13778 
.18023 
.22440 
.26818 
0.8116 
3546 
0.8973 
0.4396 
I.4S15 
0.5231 
0.5645 
0.6053 
0.6459 
0.6862 
0.7261 
0.7784;  0.7657 
0.81880.8051 
0.8587  0.8489 
.8984  0.8826 
O.9377  0.921O 
0.97680.9590 
1.0156  0.9967 
1.0541  l.«  841 


.09181 
.18719 
.15223 
.22692 
.27180 
0.3153 
O.3590 
0.4024 
0.4454 
0.4881 
0.5305 
-.5727 
0.6144 
0.6558 
0.6971 
0.7379 


0.50 


I  0.55 


0.60 


0.05 
0.10 
0.15 
0.20 
0.25 
0.30 
0.35 
0.40 
0.45 


0.65 
0.70 
0.75 
0.80 
0.S5 
0  90 
0.-3. 
l.i'O 
1.05 
1.10 

1.15 
1.20 
1.25 


;o.       0. 

1 .04564  .04521 
1 .09091  .09001 
j. 13778  .13438 
.18 '28  .17835 
I .22440  .22190 
1. 26818 '.  26507 
!". 3116  0.8078 
!  1. 3546  0.85  >2 
;".8973  0.3922 
10.4396  0.4338 
JO  4815  0.4750: 
10.5231  0.5158' 
0.5645  0.5563 
io. 6053  0.5964 
i 0.6459  0.6361 
i 0.6362  0.6755, 
10.7261  0.7145 
0.7657  m.  7532 
0.8051  .7916 
0.8439  0.8295 
0.8326  .8671 
0.921-0.9  45 
0.9590  0.9415 
0.9967  0.9781 
i 1.0341  1.0145 
I  1 


0. 

.04478 

.08911 

.13299 

.17643 

.21942 


0.65 


0.3041 
0.8458 
0.3871 

0.4280 
0.4835 
O.50S6 
0.54S3 
0.5875 
0.8264 
0.6650 
0.7031 
0.7409 
0.7783 
0.8153 
0.8520 
0.8883 
0.9243 
0.9599 
0.9953 


0. 

.('4435 
.08821 
.18160 
.17451 
.21694 
.25S90 
0.8  04 
'.8415 
0.8821 
0.4223 
0.4621 
0.5014 
•  ».5403 
0.57881 
0.6169 
0.6546 
0.6919 
0.7288 
0.7652 
0.8014 
0.8871 
0.8725 
".9  75 
0.9421 
0.9764 


0.70  I  0.75 


04392 
.08732 
.18  21 
.17259 
.21448 
.25583 
0.2963 
0.3372 
".8772 
0.4167 
0.4557 
'.4943 
0.5325 

.57  2 
0.6"75 
-.6443 
0.6308 
0.7168 
0.7524 
'.7876 
0.8225 
0.8570 
O.8909 
0.9246 
0.9579 


0. 

.04349 

.08644 

.128&3 

.17069 

.21203 

.25235 

0.2932 

0.3*30 

0.8723 

0.4111 

0.4494 

0.4873 

0.5247 

0.5616 

0.59S1 

0.6342 

0.6698 

0.7  00 

0.739S 

".7741 

0.8081 

0.8417 

0.8747 

0.9075 

0.9398 


0.89 


0.S5  I  0.90 


0.95 


0. 

.04263 

.08466 

,12608 

.16091 

.20715 

.94892 

0.2S59 


0. 

.04306 
.08555 
.12746 
.16880 
.20958 
.24983 
|0.2S95,  .. 
'0.32S7  0.8946 
I ".8674 1 0.3625 
'0.4055  O.4000 
0.44890.4870 
0.4804  0.4735 
'0.5170  0.5093 
0.5532  0.5448 
I ".5889  0.5793 
0.0242  0.6143 
0.6588  0.6432 
10. 6934J  0.6819 
o.7273!o.7149 
I 0.7608  ".7476 
0.7939  0.7798 
0.8265". 8116 
0.85880.8430 
0.8906  0.8739 
0.9990  0.9046 


0.  0. 
.04221  .04178 
.08878  .08289 
.12471  .12334 
.16503  .16315 
.20478  .20233 
.24888  .94087 
0.9894|0.9788 
0.8203  0.3162 
0.3577  0.8529 
".89450.8891 
0.4308  0.4247 
0.4666  0.4598 
0.5018  0.4944 
0.6865.0.6284 
.5708  0.6619 
0.6045  0.5949 
0.68770.6278 
0.6706  0.6594 
0.702S  0.6909 
0.7341  0.7219 
0.7660  0.7525 


0.2753 
0.3121 
0.34S2 
0.3833 
0.4187 
0.4531 
0.4870 
0.5203 
0.5531 
0.5854 
0.6171 
0.6484 
0.6792 
0.7094 
.7393 
0.7970  0.7897  0.7688 
0.8275  0.81 24; 0.7975 
0.8576  0  8416  0.8260 
0.S873  0.8705  0.8540 


1.00 


.04136 

.08202 
.12198 
.16128 
,19994 


TABLE  FOR  BALLISTIC  MACHINE. 


515 


Table  of  Times,  calculated  for  the  West  Point  Ballistic 
Machine. 

2*1 

L  ngth  of  simple  pendulum,  5.769  in.;  and  ; =0.001509' 

360y2gl 


Time  of 

Time  of 

1 

Degrees. 

passage  for 
each  degree. 

Sum  of  Times. 

Degrees 

passage  for 
1  each  degree. 

Sum  of  Times. 

1 

.00151 

' 

26 

.01)159 

.03987 

2 

.00151 

.00302 

27 

.00159 

.04146 

3 

.00151 

.00453 

28 

.00160 

.04306 

4 

.00151 

.00604 

29 

.00161 

.04467 

5 

.00151 

.00755 

30 

.00162 

.04629 

6 

.00151 

.00906 

31 

.00163 

.04792 

7 

.00151 

.01057 

32 

.00163 

.04955 

8 

.00151 

.01208 

33 

.00164 

.05119 

9 

.00151 

.01359 

34 

.00165 

.05284 

10 

.00152 

.01511 

35 

.00166 

.05450 

11 

.00152 

.01663 

36 

.00167 

.05617 

12 

.00152 

.01815 

37 

.00168 

.05785 

13 

.00152 

.01967 

38 

.00170 

.05955 

14 

.00153 

.02120 

39 

.00171 

.06126 

15 

.00153 

.02273 

40 

.00172 

.06298 

16 

.00153 

.02426 

41 

.00173 

.06471 

17 

.00154 

.02580 

42 

.00175 

.06646 

18 

.00154 

.02734 

43 

.00176 

.06822 

19 

.00155 

.02889 

44 

.00178 

.07000 

20 

.00155 

. 03044 

45 

.00179 

.07179 

21 

.00156 

.03200 

46 

.00181 

.07360 

22 

.00156 

.03356 

47 

.00182 

.07542 

23 

.00157 

.03513 

48 

.00184 

.07726 

24 

.00157 

.03670 

49 

.00186 

.07912 

25 

.00158 

.03828 

50 

.00188 

.08100 

Example. — What  is  the  velocity  of  a  projectile  when  the  time  of 
its  passage  between  two  targets,  100  feet  apart,  corresponds  to  20.5 
degrees  of  the  graduated  arc  ? 


Time  of  20D    : 
Add  for  0.5° 

Time  of  20°  .5 


0.03044 
0.00077 

0.03121 
2 


Log.  of  100  =  2.000000 
Log.  0.06242  ~  2.795324 


Log.    1602.     =  3.204676 


Double  arc     s  0.06242 


Velocity  ss   1602.  feet. 


516 


TABLES    OF    FIRE. 

4 


TABLES    OF   FIRE 


RANGES. 

The  range  of  a  shot  or  shell  is  the  first  graze  of  the  ball  on  horizontal  ground, 
the  piece  being  mounted  on  its  appropriate  carriage. 

The  range  of  a  spherical  case-shot  is  the  distance  at  which  the  shot  bursts 
near  the  ground,  in  the  time  given ;  thus  showing  the  elevation  and  the  length 
of  fuse  required  for  certain  distances. 


Kind  of  Ordnance. 

Powder. 

Ball. 

Eleva- 
tion. 

Range. 

Remarks. 

Lbs. 

o     / 

Yards. 

6-PDR.  FIELD   GUN. 

1.25 

Shot. 

0 

1 

2 
3 
4 
5 

318 
674 

867 
1138 
1256 
1523 

1.25 

Sph.  case 

1 

600 

Time,  2  seconds. 

shot. 

1  45 

700 

<•     H     » 

2 

800 

i,      3         u 

2  45 

900 

,      H       , 

3 

1000 

u      3f       , 

3  15 

1100 

"      4      .  « 

4 

1200 

u      5 

12-PDR.  FIELD   GUN, 

2.5 

Shot. 

0 

347 

Model  1841. 

« 

1 

1  30 
2 
3 

4 
5 

662 

785 

909 

1269 

1455 

1663 

2.5 

Sph.  case 

1 

6U0 

Time,  If  seconds. 

shot. 

1  45 

700 

"      2i        " 

2 

800 

«      21        u 

2  15 

900 

u      3 

2  30 

1000 

M          H             U 

3 

1100 

«      4 

• 

3  30 

1200 

"      4^        « 

TABLES    OF    FIRE. 
Ranges — Continued. 


517 


Kind  ov  Ordnance. 

Powder. 

Ball. 

Eleva- 
tion. 

Eange.                    Eemarks. 

Lbs. 

c      / 

Yards. 

12-PDR    FIELD   GUN, 

2.5 

Shot. 

0 

325 

Model  1857. 

i. 

1 
2 
3 
4 

620 

875 
1200 
1320 

ii 

5 

1680 

1 

2.5 

Sph.  case 

0  30 

II 
300     Time,  1  second. 

shot. 

1 

575  ' 

"      1|      « 

" 

1  30 

633 

"      2|     " 

ii 

2 

730 

it      3        ii 

" 

3 

960    1      "      4       " 

M 

3  30 

1080    1      "      4f     " 

" 

3  45 

1135 

II        5          M 

2.0 

Shell. 

0 

300 

u       0£      U 

" 

0  30 

425 

„        ^      u 

ii 

1 

616 

u       !|     ii 

u 

1   30 

700 

ii       ^     ii 

" 

2 

787 

'•      2f     « 

" 

2  30 

925  ! 

"      3i     " 

" 

3 

1080 

M        4         II 

II 

3  45 

1300 

ii      jj       ii 

12-PDR.     FIELD    HOW- 

1.0 

Shell. 

0 

195 

ITZER. 

II 

1 
o 

3 

4 
5 

539 
640 
847 
975 
1072 

0.75 

Sph.  case 

2   15 

485 

Time,  2  seconds. 

shot. 

3  15 

715 

i.      3 

it 

3  45 

1050 

«      4 

12-PDR.     MOUNTAIN 

0.5 

Shell. 

0 

170 

HOWITZER. 

ii 

1 
2 

300 
392 

" 

2   30 

500 

Time,  2  seconds. 

II 

3 

637 

" 

4 

785 

ii      3        i| 

II 

5 

1005 

0.5 

Sph.  case 

0 

150 

shot. 

2   30 

450 

Time,  2  seconds. 

518 


TABLES    OF    FIRE. 
Ranges — Continued. 


Kind  of  Ordnance. 

Powder. 

Ball. 

Eleva- 
tion. 

Eange. 

Remarks. 

Lbs. 

o     / 

Yards. 

12-PDR.     MOUNTAIN 

0.5 

Sph.  case 

3 

500 

howitzer — Con- 

shot. 

4 

700 

Time,  2£-  seconds. 

tinued. 

4  30 

800 

ii      3          ii 

24-PDR.   FIELD  HOW- 

2.0 

Shell. 

0 

295 

ITZER. 

it 

1 

516 

u 

2 
3 

193 
976 

u 

4 

1272 

u 

5 

1322 

2.5 

Sph.  case 

1  30 

600 

Time,  2  seconds. 

shot. 

2 

700 

,1         2i         u 

M 

2  30 

800 

II         3£          M 

» 

M 

2  45 

900 

"      3*      " 

(( 

3  15 

1000 

u     4 

H 

3  45 

1100 

„      4^       N 

(( 

3  50 

1200 

M       4|        u 

32-PDR.    FIELD    HOW- 

2.5 

Shell. 

0 

290 

ITZER. 

II 

1 

53  L 

M 

2 

779 

<t 

3 

1029 

M 

4 

1203 

M 

5 

1504 

3.25 

Sph.  case 

1  30 

600 

Time,  2  seconds. 

shot. 

2 

700 

m       2i       " 

m 

2  15 

800 

u      3 

M 

2  45 

900 

"      3£      " 

" 

3 

1000 

II       3j       M 

(( 

3  35 

1100 

«      4±      " 

(( 

3  45 

1200 

u      4|      u 

18-PDR.   SIEGE  AND 

4.5 

Shot. 

1 

641 

GARRISON  GUN. 

" 

2 

950 

On  barbette  carriage. 

u 

u 

3 

4 
5 

1256 
1450 
1592 

24-PDR.   SIEGE  AND 

6.0 

Shot. 

0 

412 

GARRISON  GUN. 

ii 

1 

842 

On  siege  carriage. 

« 

1  30 

953 

H 

2 

1147 

11 
U 

3 

4 

1417 
1666 

ii 

5 

1901 

TABLES    OF    FIRE. 
Ranges — Continued. 


519 


Kind  of  Okdnance. 

Powder. 

Ball. 

Eleva- 
tion. 

Range. 

Remarks. 

Lbs. 

o     / 

Yards. 

32-PDR.    SEA-COAST 

6.0 

Shot. 

1  45 

900 

GUN. 

8.0 

1 

713 

On  barbette  carriage. 

1  30 

1  35 

2 

3 

4 

5 

800 
900 
1100 
1433 
1684 
1922 

42-PDR,    SEA-COAST 

10.5 

Shot. 

1 

775 

GUN. 

u 

2 

1010 

On  barbette  carriage. 

u 

3 

4 
5 

1300 
1600 
1955 

8-INCH  SIEGE  HOW- 

4.0 

Shell, 

0 

251 

ITZER. 

45  lbs. 

1 

435 

On  siege  carriage. 

2 
3 
4 
5 
12  30 

618 

720 

992 

1241 

2280 

8-INCH    SEA-COAST 

4.0 

Shell, 

1 

405 

HOWITZER, 

45  lbs. 

2 

652 

On  barbette  carriage. 

3 
4 
5 

875 
1110 
1300 

6.0 

1 
2 
3 
4 
5 

572 

828 

947 

1168 

1463 

8.0 

1 
2 
3 
4 
5 

646 

909 

1190 

1532 

1800 

10-INCH    SEA-COAST 

12.0 

Shell, 

1 

580 

HOWITZER. 

90  lbs. 

2 

891 

Time,  3  seconds. 

On  barbette  carriage. 

M 

3 
3  30 

1185 
1300 

"     4        " 

ti 

4 

1426 

M     -5i        u 

II 

5 

1650 

u      6 

520 


TABLES    OF    FIRE. 

Ranges — Continued. 


Kind  of  Ordnance. 

Fowder. 

Ball. 

Eleva- 
tion. 

Range. 

Remarks. 

Lbs. 

o     ' 

Yards. 

8-IN.   COLUMBIAD.* 

10.U 

Shell, 

1 

081 

Time,  1.88  seconds. 

50  lbs. 

2 

1108 

"      3.58         " 

"    , 

3 

1400 

"      4.30 

" 

4 

1649 

"      5.41 

u 

5 

1733 

"      6.25 

u 

G 

1994 

"      7.56 

" 

7 

2061 

"      7.96 

M 

8 

2250 

"      9.12 

ii 

9 

2454 

'•    10.16 

it 

10 

2664 

"    10.91 

" 

11 

2718 

"    11.3 

u 

12 

2908 

"    13.0 

i 

" 

13 

3060 

"    14.08 

" 

14 

312:5 

"    14.25 

" 

15 

3138 

"    16.0 

" 

20 

3330 

"    18.40 

ii 

25 

3474 

"    20.0 

" 

30 

3873 

"    25.0 

Shot. 

5 

1697 

"      6.20 

" 

15 

3224 

"    14.19 

10-IN.     COLUMBIAD.* 

15.0 

Shell, 

3 

1068 

Time,  3.20  seconds. 

100  lbs. 

5 

1525 

"      5.64 

< 

8 

-2238 

"      8.10 

1 

10 

2720 

"    10.98         " 

' 

12 

2847 

"    11.73         " 

' 

20 

3842 

"    18.92 

4 

30 

4836 

"    27.50 

SI 

ot, 

15 

3281 

"    14.32 

125 

lbs. 

30 

5  1  63 

"    27.08 

18.0 

i 

0 

1 

2 

3 

4 

5 

6 

8 

10 

15 

20 

25 

30 

35 

394 
752 
1002 
1230 
1570 
1814 
2037 
2519 
"27  77 
3525 
4020 
4304 
4761 
5433 

Axis   of    p-un    1 1    Let 
above  the  water. 

Shot  ceased  to  ricochet 
on  water. 

20.0 

" 

39  15 

5654 

12.0 

Shell, 

1 

800 

100  lbs. 

ii 

2 
3 

1012 
1184 

*  Axis  of  gun  6  fret  above  the  horizontal  plane. 


TABLES    OF    FIRE. 
Ranges — Continued. 


521 


Kind  of  Ordnance. 

Powder. 

Bull. 

Eleva- 
tion. 

.       1 

Eange. 

! 

Iicmarks. 

Lbs. 

0 

Yards. 

10-IN.    COLUMBIAD 

12.0 

Shell, 

4 

1443 

Continued. 

100  lbs. 

5 

1604 

18.0 

u 
M 

tl 

0 
1 
2 
3 
4 

448 

747 

1100 

1239 

1611 

(( 

H 

5 
6 
8 
10 
15 
20 
25 
30 

1865 
2209 
2489 
2848 
3200 
3885 
4150 
4651 

, 

35 

4828 

Time  of  flight,  35  sec. 

15-1N.     COLUMBIAD. 

40.0 

Shell, 

0 

273 

302  lbs. 

1 
2 

484 

812 

M 

3 

1136 

II 

4 
5 

1310 
1618 

II 

G 

7 

1760  i 
1948 

315  lbs. 

8 

2194 

" 

9 

2236 

Time,   8.87  seconds. 

" 

10 

2425 

"    10.00 

" 

12 

2831 

"    12.07 

15 

3078 

"    13.72 

" 

20 

3838 

•'    17.82 

u         * 

tl 

25 
28 
30 

4528 
4821 
5018 

':    22.03 
-    24.18 
"    26.71 

45.0 

" 

25 

4595 

•'    23.20 

50.0 

II 

25 

4680 

"    23.29        " 

10-INCH    SEA-COAST 

Shell, 

i 

MORTAR. 

10.0. 

98  lbs. 

45 

4250 

Time,  36  seconds. 

10-INCH   SIEGE   MOB- 

1.0 

Shell, 

45 

300 

Time,  6£  seconds. 

TAR. 

1.5 

90  lbs. 

45 

700 

ii    12 

2.0 

« 

45 

1000 

,i    14 

2.5 

" 

45 

1300 

<i    16 

3.0 

" 

45 

1600 

u     ]8 

3.5 

" 

45 

1800 

ii     10            ii 

4.0 

45 

2100 

ii    21            ti 

522 


TABLES    OF    FIRE. 
Ranges — Continued. 


Kind  of  Ordnance. 

Powder. 

Ball. 

Eleva- 
tion. 

Range. 

Remarks, 

Lbs.  oz. 

0 

Yards. 

8-IXCH  SIEGE  MORTAR. 

10 

Shell, 

45 

500 

Time,  10  seconds. 

13 

46  lbs. 

45 

600 

ii      n 

1 

" 

45 

750 

"      12J       u 

1     2 

u 

45 

900 

.i      13         u 

1     3 

" 

45 

1000 

"      13*       " 

1     4 

" 

45 

1100 

u       14 

1     6 

45 

1200 

"      14*       " 

Oz. 

24-PDR.     COEHORN 

0.5 

Shell, 

45 

25 

MORTAB. 

1.0 

17  lbs. 

45 

68 

1.5 

u 

45 

104 

1.75 

u 

45 

143 

2.0 

u 

45 

165 

2.75 

M 

45 

260 

4.0 

« 

45 

422 

6.0 

(( 

45 

900 

8.0 

M 

45 

1200 

Lbs. 

10-PDR.     PARROTT 

1.0 

Shot, 

0 

380 

Time,  1£  second. 

and 

10  lbs. 

1 

645 

II           J£           H 

3 -INCH  RIFLE   GUN. 

ii 

2 

1000 

H         2|         II 

u 

3 

1300 

ii      4 

u 

4 

1525 

..   4f    1. 

ii 

5 

1835 

1.    6 

u 

6 

2100 

"    Ii    " 

il 

7 

2325 

u      8 

(i 

10 

2900 

ii    n 

(( 

12 

3270 

41    13 

II 

15 

3820 

"    15*      " 

II 

20 

5000 

II    19|       u 

ii 

25 

5600 

"    23*      M 

ii 

30 

5900 

"    27*      " 

u 

35 

6200 

"    31*      u 

20-PDR.   PARROTT. 

2.0 

20  lbs. 

5 

2200 

i< 

10 

3500 

u 

15 

4400 

100-PDR.   PARROTT. 

10.0 

100  lbs. 

10 

3555 

jti 

15 

4940 

ii 

20 

5301 

84  lbs. 

10 

3897 

u 

15 

5301 

ii 

20 

6300 

TABLES    OF   FIRE.  523 

Ranges  with  Sea-coast  13-inch  Mortars,  $6°  elevation. 


Charge. 

Mean  time  of 
night. 

Least  range. 

Greatest  range. 

Mean  range. 

Lbs. 

Seconds. 

Yards. 

Yards. 

Yards. 

4 

8 

840 

877 

869 

6 

9.5 

1209 

1317 

1263 

8 

11.66 

1653 

1840 

1744 

10 

12.50 

2010 

2128 

2066 

12 

14.25 

2369 

2688 

2528 

14 

15.25 

2664 

2780 

2722 

Ranges 

with  13-inch  Mortars,  at  45°  elevation. 

13-inch  Mortar. 

Powder. 

Shell. 

Elevation. 

Range. 

Lbs. 
20 

Lbs. 
200 

45° 

Yards. 
4325 

Ranges  with  13-inch  Mortars,  at  45°  elevation. 


Charge. 

Flight 

Fuze. 

Range. 

Lbs.   oz. 

Seconds. 

Inches.  lOths. 

Yards. 

7 

21.4 

4        2* 

2190 

7     8 

22.4 

4        4 

2346 

8 

23.2 

4        6 

2480 

8     8 

23.8 

4        I* 

2600 

9 

24.4 

4        8f 

2734 

9     8 

24.9 

4        9f 

2853 

10 

25.4 

5        1 

2958 

10     8 

25.9 

5        1£ 

3026 

11 

26.3 

5        2± 

3150 

11     8 

26.7 

5       H 

3246 

12 

27.0 

5        4 

3327 

12     8 

27.4 

5        4£ 

3404 

13 

27.7 

5       H 

3470 

13     8 

28.0 

5        6 

3552 

14 

28.3 

5        6£ 

3617 

14     8 

28.5 

5        7 

3681 

15 

29.0 

5        8 

3739 

15     8 

29.1 

5        8± 

3797 

16 

29.2 

5        8£ 

3849 

16     8 

29.4 

5        8£ 

3901 

17 

29.6 

5        9 

3949 

17     8 

29.8 

5       H 

3997 

18 

29.8 

5        9£ 

4040 

18     8 

30.0 

6        0 

4085 

19 

30.2 

6        0* 

4123 

19     8 

30.3 

6        0£ 

4160 

20 

30.5 

6        1 

4200 

APPENDIX 


APPENDIX 


ARMSTRONG   GUN. 


1.  Description  of  piece.  The  following:  description  of  the  Arm- 
strong gun  is  principally  gathered  from  Sir  Howard  Douglas's  Naval 
Gunnery  and  the  Official  Manual  of  Artillery  Exercises.  Although 
wanting  in  some  of  the  details,  it  is  more  complete  and  correct  than 
that  given  in  the  preceding  pages. 

Body  of  the  piece.  The  body  of  the  piece  is  made  up  by  welding 
together  several  wrought-iron  tubes ;  each  tube  is  from  two  to  three 
feet  long,  and  is  formed  by  twisting  a  square  bar  of  iron  around  a 
mandrill,  and  welding  the  edges  together.  Thus  far  the  piece  resem- 
bles the  barrel  of  a  fowling-piece.  To  strengthen  the  barrel  at  and  in 
rear  of  the  trunnions,  it  is  enveloped  with  two  additional  thicknesses, 
or  tubes.  The  outer  tube,  like  the  inner  one,  consists  of  spiral  coils ; 
but  the  intermediate  tube  is  formed  of  an  iron  slab,  bent  into  a  cir- 
cular shape  and  welded  at  the  edges.  The  reason  for  this  distinction 
is,  that  the  intermediate  layer  has  chiefly  to  sustain  the  pressure  on 
the  bottom  of  the  bore,  while  the  other  layers  are  formed  to  resist  the 
tangential  strain. 


Fig.  155. 
Breech.      The   breech,  is    closed   with    a    vent-piece    (6),   fig.   155, 
which  is  slipped  with  the  hand  into  a  slot  cut  in  the  breech  of  the 
piece,  and  held  in  its  place  by  a  breech-screw  (a),  which  supports  it 
from  behind. 


528 


APPENDIX. 


This  screw  is  made  in  the  form  of  a  tube,  so  that  its  hollow  forms  a 
part  of  the  bore  prolonged,  when  the  vent-piece  is  withdrawn.  The 
object  of  this  hollow  is  to  allow  the  charge  to  be  passed  into  the 
chamber. 

Bore.  The  bore  of  the  field-gun,  which  is  represented  in  the  draw- 
ing, is  three  inches  in  diameter,  and  it  is  rifled  with  thirty-four  narrow 
grooves.     Twist,  one  turn  in  9  feet. 

The  diameter  of  the  chamber  is  one-eighth  of  an  inch  larger  than 
that  of  the  bore. 

Vent.  The  vent  is  formed  in  the  breech-piece  in  order  that,  when 
it  becomes  enlarged,  it  may  be  easily  replaced.  For  this  purpose, 
spare  breech-pieces  are  carried  with  each  battery.  The  diameter  of  the 
vent  is  \  inch,  and  it  is  primed  by  filling  it  with  a  small  paper  car- 
tridge of  fine  powder,  which  is  ignited  by  an  ordinary  friction-tube. 

It  is  not  stated  whether  the  gas  is  allowed  to  escape  through  the 
joint;  but  it  was  shown  in  the  experiments  made  at  West  Point,  that 
the  escape  can  be  easily  prevented  by  a  gas-check  of  soft  metal  (/). 

Projectile.  Only  one  kind  of  projectile  is  used  for  field-guns,  and 
that  is  so  constructed  that  it  may  operate  as  a  shot,  shell,  or  case-shot, 
at  pleasure. 

It  consists — see  figure  156 — of  a  very  thin  cast-iron  shell  (^4  A), 
enclosing  forty-two  segment-shaped  pieces  of  cast 
iron  (B  B),  built  up  so  as  to  form  a  cylindrical 
cavity  in  the  centre  (D),  which  contains  the  burst- 
ing-charge and  the  concussion-fuze.  The  exterior 
of  the  shell  is  thinly  coated  with  lead  (C  (7),  which 
is  applied  by  placing  the  shell  in  a  mould  and  pour- 
ing it  in  a  melted  state.  The  lead  is  also  allowed  to 
percolate  among  the  segments,  so  as  to  fill  up  the 
interstices,  the  central  cavity  being  kept  open  by  the 
insertion  of  a  steel  core. 

In  this  state  the  projectile  is  so  compact  that  it 
may  be  fired  through  six  feet  of  hard  timber  without 
injury ;  while  its  resistance  to  a  bursting-charge  is  so 
small,  that  less  than  one  ounce  of  powder  is  required 
to  burst  it.  When  the  projectile  is  to  be  fired  as  a 
shot,  it  requires  no  preparation ;  but  the  expediency 
of  using  it  otherwise  than  as  a  shell  is  much  doubted. 


ARMSTRONG    GUN.  529 

To  make  it  available  as  a  shell,  the  bursting-tube,  the  concussion  and 
time  fuzes,  are  all  to  be  inserted ;  the  bursting-tube  entering  first,  and 
the  time-fuze  being  screwed  in  at  the  apex.  If  then  the  time-fuze  be 
correctly  adjusted,  the  shell  will  burst  when  it  reaches  within  a  few  yards 
of  the  object ;  or,  failing  to  do  so,  it  will  burst  by  the  concussion-fuze 
when  it  strikes  the  object,  or  grazes  the  ground  near  it.  If  it  be  required 
to  act  as  a  canister-shot  upon  an  enemy  close  to  the  gun,  the  regulator 
of  the  time-fuze  must  be  turned  to  the  zero  of  the  scale,  and  then  the 
shell  will  burst  on  leaving  the  gun. 

The  explosion  of  one  of  these  shells  in  a  closed  chamber,  where  the 
pieces  could  be  collected,  resulted  in  the  following  number  of  frag- 
ments : — 

106  pieces  of  cast  iron;  90  pieces  of  lead,  and  12  pieces  of  fuze, 
&c. ;  making  in  all  217  pieces. 

Fuzes.  The  time  and  concussion  fuzes  may  act  together  or  sepa- 
rately. 

The  body  of  the  time-fuze  is  made  of  pewter,  and  the  composition  is 
arranged  in  a  circular  trough,  as  in  the  Bormann  fuze.  As  the  shell 
fits  accurately  into  the  chamber,  there  is  no  passage  of  the  flame  by 
which  the  fuze  can  be  ignited ;  this  defect,  however,  is  obviated  by 
attaching  a  small  striker  to  the  fuze,  which  breaks  from  its  fastenings 
by  its  inertia,  when  the  piece  is  fired,  and  impinges  against  and  explodes 
a  small  charge  of  percussion-powder. 

The  flame  from  the  percussion  powder  acts,  through  a  small  channel, 
upon  any  desired  point  of  the  circular  column,  simply  by  turning  the 
piece  in  which  the  channel  is  formed,  so  that  the  orifice  shall  rest  upon 
the  point  of  ignition. 

The  concussion-fuze  is  made  on  the  same  principle  as  the  concussion 
arrangement  of  the  time-fuze.  A  striker,  with  a  point  to  the  front,  is 
secured  in  a  tube  by  a  wire  fastening,  which  is  broken  on  firing  the 
gun ;  the  striker,  being  liberated,  recedes  through  a  small  space,  and 
rests  at  the  bottom  of  the  tube,  but  as  soon  as  the  shell  meets  with  any 
check  in  motion,  the  striker  runs  forward  and  pierces  the  percussion- 
powder  in  front,  by  which  means  the  bursting-charge  is  ignited. 

Loading.     The  piece  is  loaded  by  placing  the  projectile  (e),  with  the 

greased  wad  (d)  and  cartridge  (c),  in  the  hollow  of  the  breech-screw, 

and  pushing  them,  separately  or  collectively,  by  a  rammer,  into  the 

bore. 

34 


530  APPENDIX. 

The  vent-piece  is  then  dropped  into  its  place,  and  secured  by  a  half- 
turn  of  the  screw-handle  Qi). 

In  the  early  guns,  it  was  necessary  that  the  portion  of  the  bore  which 
was  occupied  by  the  shot  should  be  perfectly  clean,  otherwise  the  shot 
would  not  always  enter  its  place.  It  was  necessary,  therefore,  to  use  a 
wet  sponge ;  but,  in  the  new  guns  now  issued  for  service,  a  slight  alter- 
ation in  the  bore  permits  a  greased  wad  to  be  employed  with  perfect 
success,  as  a  substitute  for  the  sponge.  The  gun  can  now  be  fired  with 
great  rapidity,  and  apparently  for  any  length  of  time,  without  being 
sponged  at  all. 

The  cartridge  is  made  of  serge,  shaped  to  fit  the  chamber  easily.  The 
powder  for  these  guns  is  slower  than  that  generally  used  in  service ;  it 
contains  a  smaller  proportion  of  nitre,  and  is  worked  one  hour  instead 
of  three.  Although  this  powder  is  better  suited  to  the  Armstrong  guns, 
giving  much  greater  regularity  of  range  and  deflection,  yet  the  service- 
powder  may  be  used  whenever  necessary.  The  charge  is  one-eighth  of 
the  weight  of  the  projectile. 

Range  and  deflection.  The  velocity  of  the  Armstrong  projectile 
diminishes  very  little  with  the  range ;  consequently  the  range  will  be 
nearly  as  the  time  of  flight.  The  velocity  averages  about  950  feet  per 
second. 

Up  to  500  yards,  one  minute  of  elevation  may  be  assumed  to  give 
10  yards  range. 

From  500  to  1,000  yards,  one  minute  of  elevation  gives  1  yards 
range. 

From  1,000  to  3,000  yards,  one  minute  gives  6  yards;  at  distances 
above  3,000  yards,  one  minute  gives  5  yards. 

The  Armstrong  guns  always  throw  to  the  right,  increasing  with  the 
range ;  this  is  termed  a  constant  deflection  (drift?),  and  must  be  allowed 
for ;  and  for  this  purpose  the  rear  sight  is  susceptible  of  a  lateral  mo- 
tion or  adjustment. 

Eight  degrees  of  elevation  give  a  range  of  about  3,000  yards. 
Carriage.      In  connection  with  the  elevating  apparatus,   the   field- 
carriages  have  a  means  for  giving  a  slight  transverse  motion  to  the  piece 
in  pointing. 

The  ship  and  sea-coast  carriages  have  a  self-acting  arrangement  for 
returning  the  piece  to  battery  after  recoil. 


FIFTEEN-INCH    COLUMBIAD.  531 


15-INCH  COLUMBIAD. 


2.  Description,  &c.  The  principal  difficulties  heretofore  ex- 
perienced in  the  manufacture  of  very  large  cast-iron  cannon  were,  the 
injurious  strains  produced  by  cooling  the  castings  from  the  exterior 
and  the  enormous  pressures  arising  from  large  charges  of  powder  com- 
posed of  the  ordinary-sized  grains. 

Captain  Rodman,  of  the  ordnance  department,  who  had  been  en- 
gaged for  many  years  in  making  experiments  with  a  view  of  solving 
these  difficulties,  arrived  at  the  conclusion  that  they  could  be  entirely 
overcome :  1st.  By  cooling  the  casting  from  the  interior  by  means  of  a 
current  of  cold  water  flowing  through  a  hollow  core  ;  and,  2d.  By  the 
use  of  very  large-grained  powder,  or  by  hollow-cake  powder,  both  of 
which  kinds  burn  more  progressively  than  that  usually  employed.  Ac- 
cordingly, this  officer  was  induced  to  submit  to  the  war  department 
the  plan  of  a  cast-iron  cannon  of  much  greater  dimensions  and  power 
than  any  heretofore  tried.  The  plan  was  approved,  and  the  piece  was 
made  at  the  Fort  Pitt  Foundry,  Pittsburgh,  Pa.,  under  the  immediate 
supervision  of  its  projector. 

De  cription.  The  form  of  the  piece,  which  is  evidently  a  great  im- 
provement on  that  of  the  old  columbiads,  is  shown  in  the  accompany- 
ing figure. 


Fig.  157. 

The  principal  dimensions,  &c,  are  as  follows,  viz. : 

Diameter  of  bore, 15  inches. 

Length  of  bore,  including  elliptical  chamber,        165     " 
Weight  of  rough  casting,  .         .         .       78,000  lbs. 

Weight  of  finished  piece,  .  49,090     " 

Diameter  of  shell,  .         .         .         .  14-9  inches. 


532 


APPENDIX. 


Weight  of  shell  .         .         .         .  320    lbs. 

Bursting-charge       .         .         .  .         .    17     " 

Charge  of  piece  (large-grain  .6  in.  diam.),     .         40     " 
"  "      (cake-powder),        .         .         .     50     " 

The  mean  velocity  in  passing  over  the  first  885  feet  from  the  gun,  as 
determined  by  the  fall  of  the  projectile,  is,  for  the  grain-powder,  1,328 
feet,  and,  for  the  cake-powder,  1,282  feet. 

Ranges,  &c.  The  ranges,  time  of  flight,  elevations,  &c,  are  as  fol- 
lows : — 


POWDER. 

Elevation. 

Range. 
Yards. 

Time  of 
flight. 

Seconds. 

Kind. 

Weight, 
lbs. 

Cake 
Grain  (.6) 

M 
M 
U 
U 
« 
M 
U 
u 
if 

40 
u 

u 

35 

M 

u 

40 

M 
M 

a 

M 

(( 
M 

0 

a 
U 

6° 

M 

u 

10° 
u 

u 

28°  35' 

M 

258 
276 
293 
1,973 
1,970 
1,979 
2,700 
2,210 
2,754 
2,760 
5,435 
5,062 
5,730 

7". 

6".75 

7//. 
11".48 
11".30 
10".  80 
ll/r.06 
24,,.82 
25". 
27". 

V.                                                                       A..                                                        J 

Over  water.        At  target. 

The  axis  of  the  piece  was  13f  feet  above  the  water. 

Deviation.  The  mean  range,  at  6°  elevation,  of  ten  shots,  was  1,936 
yards ;  and  the  mean  lateral  deviation,  2.2  yards.  The  lateral  devia- 
tion for  28°  35',  as  observed  with  a  telescope  attached  to  one  of  the 
trunnions,  was  very  slight. 

Pressure.  The  pressure  on  the  surface  of  the  bore,  as  indicated  by 
Captain  Rodman's  internal  pressure  pings,  was  about  one-half  less  for 
the  cake  than  the  grain  powder ;  at  the  same  time  the  pressure  of  the 
charge  of  cake-powder  was  only  about  one-fourth  of  that  on  the  bore  of 
the  10-inch  columbiad  with  its  proper  charge  of  service-powder.  The 
comparative  pressures  are  determined  by  the  lengths  of  the  indentations 


EXPEKIMENTS    WITH    POWDER.  533 

made  in  copper ;  the  absolute  pressure  in  pounds  is  not  given  in  the 
report  from  which  this  information  is  derived. 

Endurance.  After  five  hundred  rounds,  the  bore  and  vent  were 
carefully  examined  and  measured ;  the  enlargement  of  the  former  was 
inappreciable,  while  that  of  the  latter  was  very  uniform,  and  less  than 
is  usual  in  large  cast-iron  cannon.  The  projector  infers  from  these  facts, 
that  the  piece  will  bear  1,000  rounds  without  material  injury. 

Manoeuvre.  The  piece  was  fired  from  an  iron  carriage  of  the  new 
pattern  (page  243),  and  was  manoeuvred  with  great  facility  by  a  small 
force  of  men. 

During  the  trials,  it  was  manned  with  one  sergeant  and  six  negroes, 
and  the  times  of  loading,  &c,  were  as  follows,  viz. : 

The  times  of  loading,  1'  15",  1',  and  1'  3". 

Time  occupied  in  traversing  90°,  2'  20",  and  in  turning  back  45°,  1'. 

Times  of  loading,  including  the  depression  of  the  piece  from  28° 
35',  sponging,  loading,  and  elevating  again  to  28°  35',  were  4'  and 
3'  10". 

EXPERIMENTS  WITH  GUNPOWDER. 

3.  Object.  In  the  sumWr  of  1860,  the  chief  of  ordnance  directed 
a  series  of  experiments  to  be  made  at  Fort  Monroe  and  West  Point,  to 
ascertain  the  effect  of  increasing  the  size  of  the  grains  of  cannon- 
powder. 

The  object  of  the  experiments  at  Fort  Monroe  was  to  determine  the 
pressure,  initial  velocity,  and  range,  of  various  kinds  of  powder  in  the 
larger  service-cannon  ;  while  those  at  West  Point  were  to  determine 
the  same  points  with  reference  to  the  6-pdr.  gun-pendulum,  the  results 
of  which  are  applicable  to  field-cannon. 

Description  of  powders.  The  powders  tested  were  of  two  kinds  of 
manufacture  (Hazard's  and  Dupont's),  and  ten  different  sizes  of  grains, 
as  follows : 

No.  1,         2  grains  of  powder  weighed  100  grains  Troy. 
"     2,  4 

"      3,  8 

"  4,  16 
*  5,  32 
'•  6,  64 
"     7,     128 


It 

It 

it 

it 

it 

tt 

it 

it 

it 

U 

n 

M 

14 

it 

U 

it 

it 

it 

534  APPENDIX. 

No.  8,     250  grains  of  powder  weighed  100  pounds  Troy. 
u     9)     500         u  m  u  «  « 

"  10,   1000        "  "  "  "  " 

The  size  of  the  service-grain  is  about  1,500  grains  to  the  100  grains 
Troy.  The  mean  specific  gravity  of  Dupont's  powder  was  about  1.710 ; 
that  of  Hazard's,  about  1,550,  as  taken  with  a  densimetre  a  mercure. 

Experiments.  The  instruments  employed  in  the  West  Point  ex- 
periments were  : — 

Rodman's  indenting  apparatus,  to  determine  the  pressure  on  the 
bottom  of  the  bore. 

A  6-pdr.  gun-pendulum,  to  determine  the  initial  velocity  impressed 
upon  the  projectile. 

An  electro-ballistic  machine  (Navez's),  to  determine  the  time  of  pas- 
sage of  the  ball  over  a  certain  distance  in  front  of  the  pendulum. 

And  a  plane  table,  to  obtain  the  range  of  the  projectile  over  water. 

The  position  of  the  diameter  passing  through  the  centre  of  gravity 
of  the  ball  was  determined  by  floating  in  a  bath  of  mercury,  and  it  was 
secured  in  the  axis  of  the  bore  by  means  of  a  grommet  wad. 

Table  of  the  mean  results  of  three   fires    with    each    specimen    of 
powder.      Charge,    \\  lb. 


HAZARD'S. 

DUPONT'S. 

4a 

C3  *S 

Initial  Velocity. 

a  J3 

Initial  Velocity. 

Q 

i 

a 

Cm 

0 

ft  © 

el 

3   m 

Feet. 

•E 

g 

o  .5 

Feet. 

CS 

| 

a  a 

be  3 

li 

•w>    3 

o  X 

©  3 

Ec"s 

©    3 

<J2     © 

PQ© 

«  ft 

a 

■ 

8  2 

^  a 
^  ft 

11 

1 

11,277 

1319 

1233 

281 

2,846 

786 

798 

223 

2 

9,170 

1319 

1253 

283 

4,250 

1056 

1036 

231 

3 

8.047 

1303 

1322 

256 

5,213 

1077 

1093 

237 

4 

15,860 

1333 

1330 

289  . 

8,503 

1207 

1193 

274 

5 

34,423 

1446 

1532 

265  1 

8,180 

1224 

1203 

272 

6 

47,477 

1468 

1521 

299 

8,246 

1238 

1218 

243 

7 

55.530 

1473 

1455 

28S  ; 

13,953 

1295 

1326 

258 

8 

54,140 

1476 

1474 

313 

22,730 

1345 

1345 

268 

9 

59,04G 

1436 

1502 

259  ! 

41,130 

1462 

1463 

289 

10 

64,310 

1500 

1505 

302 

40,163 

1426 

1414 

293 

Mean 

35,928 

1415 

1413 

283 

15,522 

1212           1209 

2*59 

RIFLE-PROJECTILES.  535 

4.  Conclusions  1st.  The  pressures,  initial  velocities,  and  ranges 
of  Hazard's  powders,  were  greater  than  Dupont's,  in  the  following 
ratios : 

Pressures, 2.36 

Initial  velocities — 

By  gun-pendulum,         .        .        .     1.16 

By  electric  machine,  .         .  1.1 7 

Range, 1.11 

2d.  In  both  kinds  of  powders,  the  pressures,  initial  velocities,  and 
ranges  increase,  while  the  size  of  the  grain  diminishes;  the  increase  of 
pressure,  however,  is  much  more  rapid  than  the  increase  of  initial  ve- 
locity and  range". 

3d.  In  mixed  charges  (results  not  given),  the  pressures  were  least 
in  those  which  had  the  greatest  proportion  of  large  grains ;  the  differ- 
ence in  range,  however,  was  very  slight. 

4th.  The  velocities  and  ranges  obtained  with  service-charges  of 
fine,  medium,  and  coarse  grain  powders,  in  an  18-pounder  siege-gun, 
were  nearly  alike.  The  pressure-plug  was  not  applied,  as  the  trials 
of  these  powders  in  the  heavy  guns  were  to  be  made  at  Fort  Monroe. 

The  velocities  obtained  by  the  gun-pendulum  are  more  uniform  than 
those  obtained  by  the  electric  machine,  although  the  mean  results  are 
very  nearly  the  same.  The  excess  of  the  latter  over  the  former,  in 
many  instances,  may  have  arisen  from  placing  the  wire  across  the  muz- 
zle of  the  pendulum-gun  (in  which  case  it  was  broken  by  the  flame 
before  the  ball  reached  it),  and  by  giving  too  great  a  value  to  the  con- 
stant N,  in  the  formula  for  the  velocity  by  the  gun-pendulum. 

RIFLE-PROJECTILES. 

5.  Different  systems.  The  rifle-projectiles  used 
in  the  United  States,  service  belong  to  the  expand- 
ing class.  The  following  are  among  the  most  prom- 
inent used  in  the  land  service,  viz. : 

ParrotCs.  Parrott's  projectile  is  composed  of  a  cast- 
iron  body  (a)  and  a  brass  ring  (6)  cast  into  a  rabate  at 
the  base  of  the  body  (see  fig.  158.) 

The  gas  insinuates  itself  under  the  ring,  forcing  it 
Pig  158.  outward  into  the  rifles  of  the  bore.  In  the  smaller 
projectiles    it  is  necessary  to    open   the  ring  slightly  for  the  entrance 


536 


APPENDIX. 


Fig.  159. 


of  the  gas.  Some  of  the  projectiles  used  in  Parrott's  guns  have  a 
wrought-iron  expanding  cup  attached  to  the  base,  constituting  a 
modification  of  the  Reed  projectile. 

The  iron  cups  do  not  possess  any  advantage  over 
the  brass  rings. 

SchenkWs.  Schenkle's  projectile  is  shown  in  fig. 
159.  It  is  composed  of  a  cast-iron  body  (a),  the  pos- 
terior portion  of  which  terminates  in  a  cone.  The 
expanding  portion  is  a  papier  mache  wad  (b).  which 
being  forced  forward  on  to  the  cone,  is  expanded 
into  the  rifling  of  the  bore.  On  issuing  from  the 
bore  the  wad  is  blown  to  pieces,  leaving  the  pro 
jectile  entirely  unincumbered  in  its  flight  through 
the  air. 

Hotchkiss.  Hotchkiss'  projectile  is  composed  of 
three  parts,  the  body  (a),  the  expanding  ring  of  soft 
metal  (6),  and  the  cap  (c),  see  fig.  160.  The  action, 
of  the  charge  is  to  crowd  the  cap  against  the  soft 
metal,  thereby  expanding  it  into  the  rifling  of  the 
bore. 

Sawyer.     Sawyer's    projectile    has    six   rectangular 
flanges,  corresponding   to    the   grooves    of  the    bore, 
and  therefore  belongs  to  the  flanged  class.     To  soften 
the  contact  of  the  projectile  with  the  surface  of  the 
Fig.  160.  bore,  the  entire   surface  of  the  projectile  is  covered 

with  a  soft  metal  coating  cast  on.  The  soft  metal  at  the  bottom  is 
made  thicker  than  at  the  sides  to  admit  of  being 
expanded  into  the  grooves,  and  thereby  closing  the 
windage. 

James.  The  expanding  part  of  James's  projectile 
consists  of  a  hollow  (c),  fig.  161,  formed  in  the 
base  of  the  projectile ;  and  eight  openings  (6),  which 
extend  from  this  hollow  to  the  surface,  for  the  pas- 
sage of  the  gas,  which  presses  against  and  expands 
into  the  grooves  of  the  bore,  an  envelope  or  patch 
(e),  composed  of  paper,  canvas,  and  lead,  a  repre- 
Fig.  161.  sents  the  body  of  the  projectile,  which,  in  this  case, 

is  a  solid  shot ;  and  d  is  a  partition  between  two  of  the  openings, 


INDEX 


Absolute  force  of  gunpowder,  55. 

Accidents,  from  the  spontaneous  combus- 
tion of  charcoal,  17  ;  with  percussion 
locks,  297. 

Aiming  a  fire-arm,  299. 

Air,  effect  of  the  resistance  of,  on  a  rifle 
projectile,  177  ;  resistance  of  the,  40 i ; 
fall  of  a  projectile  in  the,  404 ;  trajec- 
tory in  the,  412-424. 

Alcohol  in  pyrotechny,  347. 

Ammunition  for  small-arms,  348 ;  for 
field  and  mountain  cannon,  351;  for 
siege  and  sea-coast  cannon,  353  ;  prep- 
arations for  the  service  of,  358. 

Analysis  of  gunpowder,  30. 

Ancient  arms,  270. 

Ancient  guns.  106. 

Ancient  howitzers,  107. 

Ancient  mortars,  106. 

Ancient  theory  respecting  length  of  can- 
non, 127. 

Angle  of  arrival,  in  ricochet  fire,  453. 

Angle  of  fire,  definition  of,  437  ;  in  rico- 
chet firing,  455. 

Angle  of  sight,  definition  of,  437. 

Antimony  in  pyrotechny,  345. 

Appendix,  525. 

Armament  of  sea-coast  batteries,  503. 

Armor,  ancient,  272. 

Armor,  defensive,  286. 

Armorer,  dismounting  of  fire-arms  by  an, 
335. 

Armories  of  the  United  States,  where  sit- 
uated, 320. 

Arms,  package  and  storage  of,  330  ;  pres- 
ervation and  care  of,  when  in  service, 
332. 

Arms  in  service,  inspection  of,  336. 

Armstrong's  rifle-gun,  how  constructed, 
150;  experiments  made  with,  in  breech- 
ing, 485;  description  of,  527. 

Arquebuse,  history  and  description  of 
the,  273. 


Arsenals,  how  classified,  268. 

Artillery,  materiel  of,  108 ;  system  of, 
108  ;  first  system  of,  in  the  16th  cen- 
tury, 109;  second  system  of,  in  the 
reign  of  Louis  XIV.,  110;  Valiere's 
system  of,  110;  G-ribeauval's  system 
of,  111;  Louis  Napoleon's  system  of, 
112;  stock  trail  system  of,  112;  im- 
portant recent  improvements  in,  113 ; 
General  Paix nan's  system  of,  166  ;  im- 
plements and  machines  for,  248. 

Artillery  carriages,  classification  of,  212; 
preservation  and  repairs  of,  259;  how 
to  destroy,  259  ;  materials  for,  261- 
266 :  construction  of,  267 ;  painting 
of,  268. 

Artillery  harness,  215,  218. 

Artillery  wheel,  220. 

Astragal  of  field  guns,  115. 

Attachment  of  artillery  harness,  216- 
217. 

Austrian  army  bullet,  313. 

Axle-tree  of  the  artillery  carriage,  226; 
of  the  field  limber,  231. 

Back-action  lock,  297. 

Bags  of  powder,  explosive  force  of,  376. 

Ballistic   machine    at  West   Point,   390, 

395;   table  of  times  calculated  for,  515. 
Ballistic  machine  of  Captain  Navez,  389. 
Ballistic  pendulum,  383,  388. 
Ballistics,  history  of,  382. 
Balloting  in  the  bore  a  cause  of  rotation, 

425. 
Bands  of  portable  fire-arms,  300. 
Barbette  sea-coast  carriages,  247. 
Barrel  of  portable  fire-arms,  290;  length 

of,  316-319;   inspection  of,  328. 
Barrel  of  the  rifle-musket,  how  cleaned, 

333. 
Bar-shot,  description  of,  83. 
Base  of  the  breech  of  cannon,  115. 
Base-ring  of  cannon,  115. 


538 


INDEX. 


Battery-wagon,  how  employed,  236 ;  de- 
scription of,  237. 

Battle-axe,  ancient,  270. 

Bayonet,  origin  and  history  of  the,  276; 
description  of,  280  ;  inspection  of,  329 ; 
when  unserviceable,  337. 

Beeswax  and  tallow,  a  lubricant  for  fire- 
arms, 316;  in  pyrotechnv,  347. 

Bill-hook,   259. 

Bill  of  timber,  266. 

Blistered  steel,  how  made,  140. 

Blue  color,  how  produced  on  the  surface 
of  iron  and  steel,  326. 

Blue-light,  ingredients  for,  369. 

Bombard,  early  cannon,  104;  how  con- 
structed, 105. 

Bomford,  Colonel,  plan  of,  for  determin- 
ing pressure  of  the  charge  in  cannon, 
152;  columbiad  invented  by,  190. 

Borda,  experiments  of,  in  relation  to  the 
forms  of  projectiles,  4 1 0. 

Bore,  influence  of  length  of,  on  velocity 
of  projectile,  127 ;  effect  of  length  of, 
on  maximum  charge,  131 ;  length  of, 
in  field  cannon,  180;  use  of  projectiles 
not  suited  to,  435. 

Bore  of  Armstrong  gun,  528. 

Bore  of  cannon,  116;  inspection  of,  201  ; 
enlargement  of,  208,  210. 

Bore  of  fire-arms,  length  of,  127. 

Bore  of  rockets,  96. 

Boring  cannon,  199;  vent  of  cannon,  200; 
musket- barrels,  323. 

Bormann  fuze,  description,  362. 

Bow,  the  ancient,  271. 

Breach,  firing  in,  496. 

Breaching  walls  of  fortifications,  481 ; 
with  rifle-cannon,  485. 

Breech  of  Armstrong  gun,  527. 

Breech  of  cannon,  115;  best  form  of,  for 
strength,  120  ;  thickness  of,  157. 

Breeching  of  artillery  horses,  219. 

Breech-loading  arms,  301 ;  advantages 
of,  307. 

Breech -loading  cannon,  early,  105;  pro- 
jectiles for,  170. 

Breech-sight,  how  used,  255. 

Breech-screw  of  portable  fire-arms,  291. 

British  service  bullet,  313. 

Bronze  as  a  material  for  cannon,  138 ; 
density  and  tenacity  of,  139. 

Bronze  cannon,  copper  vent-pieces  made 
for,  117  ;  injured  by  the  melting  of  the 
tin,  139;  inspection  of,  204;  defects 
in,  205;  how  proved,  206;  liable  to 
injury  from  lodgement.  210. 

Browning  musk -t-barrels,  327. 

Buckshot  cartridge.  349. 

Budge-barrel,  for  carrying  cartridges,  252. 

Buildings  for  pyrotechny,  how  arranged, 
342. 


"  Built-up "  cannon,  noted  instances  of, 
150. 

Bullets  for  small-arms,  76  ;  present  form 
of  expanding,  312 ;  in  use  in  the  Unit- 
ed States  and  Europe,  312,  314;  elon- 
gated, proper  charge  of  powder  for, 
315;  how  made,  348;  effects  of,  486. 

Burnside's  system  of  "  packing  the  joint" 
of  breech-loading  arms,  303. 

Butt  of  a  musket,  length  and  shape  cf, 
298. 

Butt-plate  of  portable  fire-arms,  300. 

Cadet-musket,  description  of,  317. 

Caisson,  description  of  the,  235 ;  how  to 
destroy,  259. 

Cake  powder  made  by  compression  of 
grain  powder,  52;  compared  with  grain 
powder,  154. 

Calibre  of  cannon,  107  ;  of  siege  guns, 
184;  of  portable  fire-arms,  293. 

Calibres  in  the  American  service  (note), 
107. 

Canister  fire,  468 ;  of  field  artillery,  492. 

Canister-shot,  description  of,  81.    ' 

Cannon,  shape  of  the  first,  104;  early, 
construction  of,  105;  calibre  of,  107; 
devices  on,  108;  construction  of,  114; 
interior  form  of,  116;  influence  of  length 
of  bore  of,  on  velocity  of  projectile,  127; 
materials  best  adapted  for  the  construc- 
tion of,  131,  132  ;  strength  of,  how  af- 
fected by  cooling,  134;  course  of  the 
fracture  of,  in  bursting,  136 ;  materials 
principally  used  in  the  fabrication  of, 
138;  thickness  of  the  metal  of,  151; 
exterior  form  of,  151 ;  nature  of  force 
to  be  restrained  by,  153 ;  various  kinds 
of  strain  upon,  154 ;  nomenclature  of 
the  exterior  of,  157;  peculiar  form  of, 
made  in  Sweden,  159;  position  of  the 
centre  of  gravity  of,  163  ;  weight  of, 
how  determined,  165 ;  different  kinds 
of,  166 ;  rifled,  167  ;  uses  to  which  ap- 
plied, 180;  mountain  and  prairie,  183; 
for  sea-coast  batteries,  188  ;  where 
made,  194 ;  proof  of,  205 ;  bronze,  how 
proved,  206 ;  inspection  marks  on,  207  ; 
how  marked  when  rejected,  207  ;  inju- 
ries to,  caused  by  service,  207 ;  how 
disabled,  260. 

Cannon-balls,  preservation  and  piling  of, 
93. 

Carbine,  description  of,  317. 

Carcass,  description  of.  84 ;  composition 
and  preparation  of,  371. 

Carriage  of  Armstrong  gun,  530. 

Carriages,  artillery  212;  materials  for, 
261-266. 

Carronades,  description  of,  194. 

Cartridge-bags,  how  made,  352,  353. 


INDEX. 


539 


Cartridge  of  the  rifle-musket,  349. 

Cartridge  with  buckshot,  349. 

Cartridges,  materials  for  preparing,  348 ; 
for  small-arms,  how  packed,  349 ;  num- 
ber expended  in  European  wars,  469. 

Cascable  of  cannon,  parts  of  the,  114; 
knob  of  the,  163. 

Case-hardening,  the  process  of,  325. 

Casemate  carriages,  247. 

Casemate  howitzer,  193. 

Casern  ite  truck,  for  moving  cannon,  250. 

Case  of  a  signal  rocket,  366. 

Cases  for  fireworks,  how  made,  357. 

Case-shot,  description  of,  80  ;  fabrication 
of  spherical,  88  ;  when  to  be  fired  in 
defence  or  attack  of  a  work,  496. 

Cast-iron,  projectiles  of,  72;  effect  of 
cooling  on  the  strength  of  cannon  made 
of,  134;  better  adapted  for  large  than 
small  cannon,  136;  advantages  and  dis- 
advantages of,  as  a  material  for  can- 
non, 145;  causes  which  affect  the  qual- 
ity of,  145  ;  how  tested  for  cannon  met- 
al, 145;  general  properties  of,  147  ;  te- 
nacity of,  injured  by  the  presence  of 
sulphur,  149 ;  endurance  of,  211 ;  in- 
juries to  cannon  made  of,  211;  effect 
of  projectiles  on,  471. 

Cast-steelj  how  made,  and  characteristics 
of,  141. 

Cavalry,  effect  of  field  artillery  against, 
490. 

Cavalry  sabre,  description  of,  284. 

Cavities  in  cannon,  how  produced,  208. 

Centre  of  gravity  of  projectiles,  74;  effect 
of  the  position  of,  178. 

Centre  of  gravity  of  cannon,  position  of, 
163. 

Chain-ball,  proposed  to  be  attached  to 
projectiles,  75. 

Chain-shot,  83. 

Chambers  of  fire-arms,  121-123. 

Charcoal,  15;  properties  of,  16;  quality 
of,  affected  by  temperature  in  manufac- 
ture, 16;  spontaneous  combustion  of, 
1 7  ;  combustibility  of  various  kinds  of, 
18,  19 ;  influence  of  trituration  on  the 
combustibility  of,  19;  quantity  of,  in 
gunpowder,  31;  pulverized,  used  in 
the  process  of  casting  cannon,  196 ;  in 
pyrotechny,  345. 

Charge,  force  of,  influenced  by  the  form 
of  its  seat,  120;  influence  of  windage 
on  the  force  of,  125;  maximum,  130; 
the  most  suitable  for  smooth-bored 
cannon,  131  ;  proportion  of,  to  weight 
of  projectile,  131;  effect  of  length  of 
bore  on  maximum,  131;  to  determine 
the  pressure  of,  by  calculation,  151;  to 
determine  the  pressure  of,  by  experi- 
ment, 152 ;  for  field  guns  and  howit- 


zers, 181;  for  siege  guns,  185;  for 
proving  cannon,  206 ;  in  ricochet  fire, 
to  find,  455. 

Charge  of  rupture  of  shells,  84. 

Chase  of  cannon,  115  ;  thickness  of,  158. 

Chassis  for  sea-coast  gun-carriages,  245. 

Chassis-rails,  props  of,  247. 

Cheeks  of  artillery  carriages,  226. 

Chlorate  of  potassa,  used  in  the  manufac- 
ture of  gunpowder,  14 ;  in  pyrotechny, 
344. 

Classification  of  cannon,  114;  of  artillery 
carriages,  212  ;  of  arms  in  service,  339; 
of  fires,  450. 

Closing  the  breech  of  breech-loading  arms, 
302. 

Coehorn  mortar,  description  of,  188 ; 
range  of,  522. 

Coke- wash,  use  of,  in  the  process  of  cast- 
ing cannon,  198. 

Coloring  materials  in  pyrotechny,  346. 

Colt's  pistol,  description  of,  318. 

Columbiads,  history  and  description  of, 
190;  improved  model  of,  adopted  in 
1860,  191 ;  dimensions  of  the  improved, 
192 ;  large,  and  iron-plated  vessels 
(note),  473;  ranges  of,  520;  the  15- 
inch,  description  of,  531. 

Columbiad-shell,  bursting-charge  of,  355. 

Combined  metals,  as  materials  for  cannon, 
149. 

Combustibility  of  various  kinds  of  char- 
coal, 18,  19. 

Combustion  of  gunpowder,  velocity  of, 
39 ;  nature  of  the  products  of,  52  ;  gas- 
eous products  resulting  from,  53. 

Compositions  for  military  fireworks,  356; 
for  signal  rockets,  366. 

Compound  projectiles,  73. 

Compressible  fluid,  resistance  of,  403. 

Compression,  strain  by,  upon  cannon, 
154. 

Concave  cutting-edge,  action  of,  283. 

Concentric  projectiles,  effect  of  rotation 
on,  427. 

Concussion  fuze,  description  of,  364. 

Cone  of  portable  fire-arms,  292  ;  defects 
in,  337. 

Congreve  rocket,  how  guided,  99. 

Congreve,  Sir  William,  improvements 
made  by,  in  the  construction  of  rock- 
ets, 102. 

Conical  chambers  of  fire-arms,  122. 

Construction  of  artillery  carriages,  267. 

Construction  of  early  cannon,  105. 

Construction  of  cannon,  114. 

Construction  of  rockets,  94. 

Continuous  effort  exerted  by  draught- 
horses,  214. 

Convex  cutting-edge,  action  of.  283. 

Cooling  effect  of,  on  the  strength  of  can- 


540 


INDEX. 


non,  134 ;  unequal,  effects  of  in  cannon 
modified  by  time,  137  ;  influence  of,  on 
the  color  and  texture  of  cast-iron,  149. 

Cooling  cannon,  136,  198. 

Corrosion,  cannon  metal  should  be  able 
to  resist,  138. 

Counter  and  enfilading  fires  with  siege 
cannon,  494. 

Cracks  in  cannon,  how  produced,  208  ; 
on  the  exterior,  211. 

Crossbow,  the  ancient,  272. 

Cuirass  and  helmet,  description  of,  286. 

Curving  plates  for  musket-barrels,  321. 

Cuts  in  cannon,  210. 

Cutting- arms,  282. 

Cutting  and  filing  in  the  manufacture  of 
small  arms,  325. 

Culverins,  106;  very  long  one  cast  du- 
ring the  reign  of  Charles  V.,  127. 

Cylinder  and  cap  in  ammunition,  352. 

Cylinder-gauge,  201. 

Cylinder-staff,  200 

Cylindrical  chambers,  for  fire-arms,  122  ; 
injurious  effect  of*  on  heavy  cannon, 
123. 

Dahlgren,  Captain,  two  vents  placed  by, 
in  his  naval  guns,  209 ;  experiments 
of,  in  relation  to  deviation,  430. 

Damascus  steel,  how  made,  287. 

Damask  steel,  appearance  of,  how  pro- 
duced, 142. 

Dardanelles,  defence  of,  by  means  of 
stone  projectiles,  72. 

Decorations  of  signal  rockets,  367. 

Defects  in  parts  of  fire-arms,  337-339. 

Defects  of  timber  trees,  265. 

Defensive  armor,  286. 

Defensive  weapons,  ancient,  272. 

Definition  of  velocities  of  projectiles,  384. 

Deflection  of  the  Armstrong  gun,  530. 

Delvigne's  improvements  in  loading  rifles, 
309. 

Density  of  a  charge  of  gunpowder  of  cy- 
lindrical form,  62. 

Density  of  gases  developed  in  the  com- 
bustion of  gunpowder,  58. 

Density  of  gunpowder,  influence  of,  on 
the  velocity  of  combustion,  43  ;  in  re- 
lation to  force,  56. 

Derivation,  or  drift,  causes  of,  432. 

Destruction  of  artillery,  259. 

Determination  of  equations  of  motion. 
395-400. 

Deviation,  294.  424 ;  conclusion  respect- 
ing the  causes  of,  429 ;  of  oblong  pro- 
jectiles, 431 ;  effect  of  wind  in  produc- 
ing, 433;  summary  of  the  causes  of, 
433;  measure  of,  460;  vertical  and 
horizontal,  461;  with  the  15-inch  co- 
lumbiad,  532. 


Devices  on  old  cannon,  108. 

Didion,  Captain,  on  trajectory  in  the  air, 
412. 

Different  kinds  of  cannon,  166;  small- 
arms,  316:  fires,  450. 

Dimensions  of  siege  mortars,  186;  of  the 
siege  howitzer,  186. 

Direct  fire,  when  used,  450. 

Direct  fire  of  field  artillery,  490. 

Disabling  cannon,  260. 

Discharging  fire-arms,  435. 

Dish  of  the  artillery-carriage  wheel,  221. 

Dismounting  arms  by  a  soldier,  332  ;  by 
an  armorer,  335. 

Dispart  of  cannon,  116. 

Distance  of  objects,  how  estimated,  446. 

Distillation,  charcoal  made  by,  16. 

Drag-rope,  258. 

Draught-harness  of  the  artillery  horse, 
218. 

Draught-horses,  force  exerted  by,  213  ; 
table  relating  to  the  force  of,  214;  or- 
,  dinary  load  per  day  for,  215. 

Drift,  or  derivation,  causes  of,  432. 

Drifts,  for  use  in  making  fireworks,  358. 

Drilling  and  tapping  of  musket-barrels, 
323. 

Driving  the  composition  of  rockets,  367. 

Dry  compositions  for  fireworks,  356. 

Drying  gunpowder,  25. 

Ductility,  a  desirable  quality  in  cannon 
metal,  133. 

Ductility  of  wrought  iron,  144. 

Dupont's  gunpowder  compared  with  Haz- 
ard's, 534. 

Durability  of  the  musket-barrel,  339. 

Dyer,  Major,  projectiles  devised  by,  170. 

Early  cannon,  shape  of,  1 04 ;  construction 
of,  105. 

Earth,  effect  of  projectiles  on,  475;  pen- 
etrations of  projectiles  into,  479. 

Eccentric  handspike  for  sea-coast  car- 
riages, 257. 

Eccentric  projectiles,  effect  of  rotation  on, 
427. 

Eccentric  turning,  324. 

Eccentricity  in  projectiles  a  cause  of  ro- 
tation, 425. 

Eccentrometer,  uses  of  the,  426. 

Effective  range  of  field  artillery,  488. 

Effect  of  fire  in  general,  459. 

Effects  of  gunpowder,  35;  projectiles,  471. 

Elasticity  of  material  for  cannon,  132. 

Elasticity,  absence  of,  in  cast-iron  can- 
non, 145. 

Electro-ballistic  machines,  389. 

Electro-ballistic  machine  at  West  Point, 
390-395. 

Elevating  arc  of  the  sea-coast  carriage, 
245. 


INDEX. 


541 


Elevating-screw  of  the  sea-coast  carriage, 
244. 

Elongated  bullets,  proper  charge  of  pow- 
der for,  315. 

Elongated  projectile,  advantages  of,  point- 
ed out  by  Robins,  309. 

Employment  of  field  artillery,  488 ;  siege 
cannon,  493 ;   sea-coast  cannon,  502. 

Endurance  of  cast-iron  cannon,  211 ;  of 
the  15-inch  columbiad,  533. 

Enfilading  and  counter  fires  with  siege 
cannon.  494. 

Enlargement  of  bore,  how  produced,  208. 

Equations  of  motion,  406-409  ;  determi- 
nation of,  395-400. 

Equipments  and  implements  for  artillery, 
251. 

Escape  of  gas  from  breech-loading  arms, 
302. 

Etching  on  a  sword-blade,  289. 

Expanding  bullets,  present  form  of,  312. 

Expanding  projectiles,  169. 

Experiments  with  gunpowder,  533. 

Explosion  of  gunpowder,  phenomenon  of, 
38. 

Explosive  force  of  gun-cotton,  70. 

Exterior  of  cannon,  151 ;  nomenclature 
of  157. 

Fabrication  of  projectiles,  88  ;  of  sword- 
blades,  287. 

Face  of  cannon,  115. 

Fascines,  pitched,  for  incendiary  purposes, 
374. 

Fall  of  a  projectile  in  the  air,  404,  422. 

Felling  timber  for  artillery  purposes,  264. 

Field  ammunition,  351. 

Field  artillery,  range  of,  462 ;  employ- 
ment of,  488. 

Field  cannon,  how  classified,  180;  weight 
of,  180;  length  of  bore  of,  180;  charges 
of,  181;  material  for,  181;  the  Napo- 
leon, 182;  rapidity  of  fire  of,  449. 

Field  carriages,  turning  of,  232  ;  charac- 
teristics of,  234 ;  varieties  of,  234. 

Field  guns,  ranges  of,  516. 

Field  howitzers,  range  of  shells  fired 
from,  492  ;  ranges  of,  517,  518. 

Field  limber,  construction  of  the,  230. 

Field  rifle-gun,  Rodman's  (note),  182. 

Field  shells,  uses  and  range  of,  463 ;  un- 
der what  circumstances  to  be  used, 
493. 

Fillets  of  field  guns,  115. 

Filling  shells,  355. 

Fire-arms,  important  recent  improve- 
ments in,  113  ;  shape  of  the  chambers 
of,  121 ;  length  of  bore  of,  127  ;  max- 
imum charge  of,  130  ;  recoil  of,  130 ; 
strongest  near  the  bottom  of  the  bore, 
157  ;  various   modes   of  rifling,   168 ; 


portable,  273,  290  ;  loading,  pointing, 
and  discharging,  435. 

Fire-ball,  for  lighting  up  enemy's  works, 
373;  use  of,  in  attack  or  defence,  498. 

Fire,  preparations  for  communicating, 
380. 

Fire,  tables  of,  447  ;  rapidity  of,  448. 

Fire  in  general,  effect  of,  459. 

Fire  of  case-shot,  in  attack  or  defence, 
496 ;  of  the  siege  howitzer,  497 ;  of 
mortars,  499. 

Fire-stone,  description,  preparation  and 
use  of,  370,  371. 

Fireworks,  proportions  of  nitre,  charcoal, 
and  sulphur  for,  42  ;  mililary,  356 ;  for 
signals,  366;  incendiary,  370;  for  light, 
372-375;  ornamental,  376;  offensive 
and  defensive,  376. 

Firing  at  night,  444. 

Firing  in  breach,  496. 

Firing  to  effect  a  breach,  rules  for,  484. 

First  reinforce,  thickness  of,  157. 

Fixed  ammunition,  353. 

Flame  in  ornamental  fireworks,  378. 

Flats  of  portable  fire-arms,  292. 

Flight  of  projectiles,  to  determine  time 
of,  422. 

Flint-lock,  when  introduced  and  discard- 
ed, 276. 

Foot  artillery  sword,  285. 

Foot-boards  of  the  field-limber,  232. 

Force,  loss  of,  from  windage,  124 ;  nature 
of,  to  be  restrained  by  cannon,  153. 

Force  of  draught-horses,  table  relating  to, 
214. 

Force  of  gunpowder,  55 ;  relation  be- 
tween, and  density,  56 ;  when  inflam- 
mation is  instantaneous,  58  ;  when  in- 
flammation is  not  instantaneous,  60; 
when  inflammation  is  instantaneous  or 
progressive,  66. 

Forces  acting  on  a  gun-carriage,  228. 

"Forcing"  projectiles  into  rifle-barrels, 
307 

Forge,  travelling,  description  of,  236. 

Forging  a  sword-blade,  287. 

Fork  of  the  field  limber,  231. 

Form  of  a  table  of  fire,  448. 

Form  of  cannon,  151. 

Form  of  projectile,  theory  in  relation  to, 
409 ;  results  of  experiments  in  relation 
to,  411. 

Form  of  siege  guns,  185. 

Formula  for  initial  velocity,  385. 

French  army  bullets,  313. 

French  musket-barrel,  durability  of,  339. 

Friction,  the  object  of  a  carriage-wheel 
to  diminish,  221. 

Friction-powder,  composition  of,  360. 

Friction-tube  for  firing  cannon,  359. 

Front  sight  of  portable  fire-arms,  299. 


542 


INDEX. 


Funnel,  for  loading  shells,  254. 
Furnaces  in  laboratories,  343. 
Furrows  in  cannon,  how  produced,  208. 
Fuze  instruments,  253. 
Fuzes  of  the  Armstrong  projectile,  529. 
Fuzes,  percussion,  concussion,  and  time, 
360-366. 

Galileo  on  the  path  of  projectiles,  382. 

Garrison  and  siege  cannon,  184. 

Gas,  law  of  formation  of,  in  the  combus- 
tion of  gunpowder,  44,  46;  table  of 
quantities  of,  developed  from  various 
grains  of ,  gunpowder,  48;  loss  of,  by 
the  fuze-hole  of  a  shell,  87  ;  escape  of, 
from  breech-loading  arms,  302. 

Gases  developed  in  the  combustion  of 
gunpowder,  density  of,  58. 

Gauges  for  inspecting  fire-arms,  336. 

Gerbe,  in  ornamental  fireworks,  377. 

Gin,  an  instrument  for  raising  cannon, 
248. 

Glazing  gunpowder,  25. 

Globe  and  telescopic  sights  of  fire-arms, 
299. 

Gomer  chamber  of  fire-arms,  advantages 
of,  123. 

Graduation  of  rear-sights,  445. 

Grain  of  various  kinds  of  gunpowder,  27 ; 
results  of  experiments  on  six  sizes  of, 
67. 

Grained  powder  and  caked  powder,  1 54. 

Granulating  gunpowder,  24. 

Grape  and  canister,  inspection  of,  91. 

Grape  and  canister  firing,  468. 

Grape-shot,  how  composed,  80. 

Gray  iron,  characteristics  of,  147. 

Greener's  rifle  projectile,  311. 

Grenades,  79. 

Gribeauval's  system  of  artillery,  111;  his 
method  of  attaching  artillery  horses, 
217. 

Grinding  a  sword-blade,  288;  small-arms, 
325. 

Grommets  or  ring-wads,  355. 

Grooved  balls,  75. 

Grooves,  form  of,  in  rifled  fire-arms,  171 ; 
comparative  advantages  of  variable 
and  uniform,  in  rifled  fire-arms,  173; 
method  of  cutting,  in  cannon,  173; 
number,  width,  and  shape  of,  in  can- 
non, 174;  inclination  of,  in  rifled  fire- 
arms, 175,  179  ;  objects  to  be  attained 
by,  in  rifles,  294 ;  kind  adopted  by  the 
United  States  government,  295 ;  rota- 
tion produced  by,  in  gun-barrels,  294. 

Guard-bow  of  portable  fire-arms,  300. 

Guard-plate  of  portable  fire-arms,  300. 

Gum-arabic  in  pyrotechny,  347. 

Gun-carriages,  classification  of,  225  ;  im- 
portant requisites  of,  225 ;  forces  act- 


ing on,  228 ;  construction  of,  234;  sea- 
coast,  243. 

Gun-cotton,  how  prepared,  68 ;  projectile 
force  of,  69  ;  explosive  force  of,  70. 

Gun  metal,  character  of,  146 ;  density 
and  tenacity  of,  147. 

Gun-pendulum,  for  determining  veloci- 
ties, 388. 

Gun-platform,  how  constructed,  242. 

Gunner,  implements  carried  by,  254. 

Gunnery,  science  of,  382. 

Gunpowder,  general  theory  of,  7  ;  com- 
position of,  8;  manufacture  of,  21,  23; 
pressing  and  granulating,  24 ;  simple 
method  of  manufacturing,  25;  glazing, 
drying,  and  dusting,  25;  general  qual- 
ities of  good,  27  ;  inspection  and  proof 
of,  27;  size  of  grain  of  various  kinds 
of,  27;  specific  gravity  of,  28;  mercu- 
ry densimeter  for,  28 ;  initial  velocity 
of,  29;  how  packed,  30;  inspection  re- 
port as  to  the  qualities  of,  30 ;  quanti- 
ty of  charcoal  in,  31 ;  quantity  of  salt- 
petre in,  31;  hygrometric  qualities  of, 
32 ;  quantity  of  sulphur  in,  32 ;  quick- 
ness of  burning  of,  33 ;  unserviceable, 
how  restored,  33  ;  storage  and  preser- 
vation of,  34;  history  of,  35;  transpor- 
tation of,  35 ;  effects  of,  35  ;  phenom- 
enon of  explosion  of,  38 :  ignition  of, 
38;  combustion  of,  progressive,  40; 
influence  of  purity  and  proportions  of 
ingredients  on  combustion,  41;  influ- 
ence of  density  of,  on  velocity  of  com- 
bustion. 43  ;  effects  of  trituration  of  in- 
gredients, 43  ;  velocity  of  combustion 
of,  increased  by  moistening  and  sub- 
sequent drying,  44 ;  law  of  formation 
of  gaseous  products  from,  44 ;  combus- 
tion of  a  spherical  grain  of,  45 ;  com- 
bustion of  a  polyhedral  grain  of,  46; 
combustion  of  a  grain  of  ordinary,  47  ; 
inflammation  of.  49 ;  influence  of  the 
size  of  the  grain  of,  on  combustion,  49  ; 
velocity  of  inflammation  of,  diminished 
by  compression  (note)  52 ;  products  of 
the  combustion  of,  52 ;  gaseous  prod- 
ucts resulting  from  the  combustion  of, 
53  ;  for  war  purposes,  proportions  of, 
53;  temperature  of  the  gaseous  pro- 
ducts of,  54 ;  determination  of  the  force 
of,  55 ;  relation  between  the  density 
and  force  of,  56  ;  density  of  the  gases 
developed  in  the  combustion  of,  58; 
force  of,  when  inflammation  is  instanta- 
neous, 58 ;  force  of,  when  inflammation 
is  not  instantaneous,  60  ;  density  of  a 
cylindrical  charge  of,  62 ;  expansive 
force  of  instantaneous  or  progressive 
inflammation  of,  66  ;  results  on  veloci- 
ty, of  various  densities  of,  67  ;  for  prov- 


ITOEX. 


543 


ing  cannon,  205 ;  injuries  to  cannon 
from,  203 ;  in  pyrotechny,  345  ;  exper- 
iments with,  533. 
Guns,  ancient,  106;  distinguishing  char- 
acteristics of,  166;  how  proved,  206; 
how  pointed,  439;  for  sea-coast  ser- 
vice, 190;  trajectory  of  projectiles  of, 
414-418. 

Halberd,  271. 

Hale's  rocket,  98. 

Hand-arms,  ancient,  270;  classification 
of,  277  ;  general  principles  of,  277. 

Hand-grenade,  79;  description  of  Ketch- 
urn's  (note),  80. 

Handles  of  bronze  field-pieces,  163. 

Handling  the  sabre,  283. 

Hardening  and  tempering  steel,  326. 

Hardness  a  necessary  quality  in  cannon 
metal,  137. 

Hardness  of  wrought  iron,  144. 

Harness  for  artillery  horses,  215. 

Haversack,  gunner's,  for  carrying  cart- 
ridges, 252. 

Hazard's  gunpowder  compared  with  Du- 
pont's,  534. 

Head-gear  of  artillery  horses,  218. 

Heavy  charges  for  cannon,  120. 

Helmet  and  cuirass,  description  of,  286. 

History  of  gunpowder,  35 ;  of  rockets, 
102;  of  cannon,  104;  of  small-arms, 
270;  of  ballistics,  382. 

Hollow  projectiles,  cavities  of,  how  made, 
89;  inspection  of,  91,  92. 

Hollow-shot,  various  denominations,  77. 

Hotchkiss'  rifle-projectile,  536. 

Hot-shot,  hay  wads  used  for,  355 ;  how 
prepared  and  used,  372. 

Hounds  of  the  field  limber,  231. 

Howitzers,  ancient,  107  ;  characteristics 
and  uses  of  the,  166;  for  mountain 
service,  183;  for  siege  purposes,  186; 
weight  of,  180;  for  sea-coast  service, 
193;  how  proved,  206;  how  pointed, 
439;  trajectory  of  projectiles  of,  414- 
418 ;  mountain,  range  of,  463. 

Howitzer  carriages,  construction  of,  234. 

Hutton  on  the  paths  of  projectiles.  383 ; 
experiments  of,  in  relation  to  the  forms 
of  projectiles,  410. 

Hygro metric  qualities  of  gunpowder,  32. 

Ignition  of  gunpowder,  38. 

Implements  and  equipments  for  artillery, 
251. 

Incendiary  fireworks,  370. 

Incendiary  match,  how  made,  372. 

Inclination  of  grooves  in  rifled  fire-arms, 
175;  limit  of,  179. 

Inclination  most  suitable  for  grooves  in- 
rifled  fire-arms,  179. 


Incompressible  fluid,  resistance  of,  402. 

Incorporating  ingredients  of  gunpowder. 
23. 

Infantry,  effect  of  field  artillery  against, 
489. 

Inflammation  of  gunpowder,  49 ;  circum- 
stances influencing  the  velocity  of,  50; 
force  developed  by  instantaneous,  58 ; 
force  developed  by,  when  not  instan- 
taneous, 60. 

Ingredients  of  gunpowder,  21. 

Initial  velocity,  of  gunpowder,  29 ;  of 
projectile  from  rifled  fire-arms,  174 
with  American  small-arms,  316-319 
of  projectiles,  384;  causes  affecting, 
387  ;  formula  for,  385 ;  practical  rule 
for,  387 ;  determination  of,  by  experi- 
ment, 388 ;  of  a  mortar-shell,  to  find, 
421 ;  causes  which  affect,  424. 

Initial  velocities,  table  of,  with  service 
charges,  387  ;  tables  of  values  for,  508, 
514. 

Injuries  to  cannon,  caused  by  service, 
207  ;  from  the  projectile,  209. 

Inspection  of  gunpowder,  27  ;  of  projec- 
tiles, 90;  of  cannon,  200,  201;  of 
bronze  cannon,  204 ;  of  sword-blades, 
289;  of  small-arms,  327;  of  arms  in 
service,  336. 

Inspection  marks  on  cannon,  207. 

Inspection  report  as  to  the  qualities  of 
gunpowder,  30. 

Instruments  for  the  inspection  of  hollow 
projectiles,  91 ;  for  the  inspection  of 
cannon,  200. 

Interchange  of  parts  in  similar  arms, 
320,  339. 

Interior  form  of  cannon,  116. 

Iron  cannon,  how  proved,  206. 

Iron  ores  used  by  the  United  States 
government  for  the  manufacture  of 
cannon,  146. 

Iron  parts  of  a  gun-carriage,  227. 

Iron-plated  ships,  the  smaller  sea-coast 
guns  useless  against,  189 ;  effects  of 
projectiles  on,  472. 

Iron  sling-cart,  for  moving  cannon,  249. 

Irreparable  arms,  339. 

James'  rifle,  dimensions  of,  319 ;  projec- 
tile for,  536 
Javelin,  Roman,  271. 
Jets,  in  movable  fireworks,  379. 

Knob  of  the  cascable,  163. 

Laboratory,  military,  how  it  should  be 
situated,  342  ;  precautions  to  be  used 
in,  343. 

Lackering  projectiles,  93. 

Ladle,  for  withdrawing  projectiles,  252. 


544 


INDEX. 


Lampblack  in  pyrotechny,  346. 
Lance,  description  of  the,  279;  advan- 
tages of  the  use  of  the,  280  ;  mode  of 
carrying  on  horseback,  280. 
Lance,  Macedonian,  270. 

Lance,  in  ornamental  fireworks,  377. 

Land-batteries,  advantages  of,  502. 

Large  cannon  for  sea-coast  batteries,  189. 

Law  of  resistance,  402. 

Lead,  projectiles  of,  72. 

Length  of  barrel,  of  portable  fire-arms, 
294 ;  influence  of,  on  velocity  of  pro- 
jectile, 294. 

Length  of  bore,  of  fire-arms,  influence 
of,  on  velocity  of  projectile,  127 ; 
effect  of,  on  maximum  charge,  131 ; 
experiments  to  determine  the  influ- 
ence of,  128  ;  of  field  cannon,  180  ;  of 
siege  guns,  185. 

Length  of  projectiles,  effect  of,  175. 

Length  of  stock  of  field  carriages,  233. 

Level,  gunner's,  description  of,  254. 

Lever-jack,  250. 

Lifting-jack,  250. 

Light-artillery  sabre,  description  of,  284. 

Light-balls,  374. 

Light-barrel,  how  constructed,  376. 

Light  charges  for  cannon,  121. 

Limber,  object  of  the,  230 ;  for  siege 
carriages,  240. 

Limbering,  difficulty  of  the  old  system 
of,  232. 

Line  of  fire,  definition  of,  437. 

Line  of  sight,  definition  of,  436. 

Liquid  compositions  for  fireworks,  356. 

Load  of  pack-horses,  213;  of  artillery 
horses,  215;  of  field  carriages,  233. 

Loading  Armstrong  gun,  529. 

Loading  cannon,  implements  for,  251. 

Loading  fire-arms,  435;  improvements 
in,  276. 

Loading  rifles,  various  modes  of,  307. 

Lock  of  a  portable  fire-arm,  295 ;  con- 
ditions to  be  fulfilled  in  the  construc- 
tion of,  296 ;  inspection  of,  330 ;  de- 
fects in,  338. 

Lock  of  a  rifle-musket,  how  cleaned,  334 ; 
how  taken  apart,  335. 

Locking  wheels  of  artillery  carriages, 
233. 

Lodgement,  injury  to  cannon  caused  by, 
209  ;  means  used  to  prevent,  210. 

Longitudinal  strain  upon  cannon,  154. 

Long  ranges  of  siege  cannon,  493. 

Loss  of  velocity  by  resistance  of  the  air, 
406. 

Louis  Napoleon's  system  of  artillery, 
112. 

Lubricant  for  fire-arms,  315. 

Macedonian  lance,  270. 


Machines  and  implements  for  artillery, 
248. 

Magnus,  Prof,  apparatus  devised  by, 
428. 

Mallet's  monster  mortar,  how  construct- 
ed, 150. 

Manoeuvre  of  artillery  carriages,  imple- 
ments for,  256 ;  of  the  15-inch  colum- 
biad,  533. 

Manoeuvring  handspike  for  sea-coast 
carriages,  257. 

Manufacture  of  cannon,  194;  of  small- 
arms,  320;  of  sword-blades,  287. 

Marks,  inspection,  on  cannon,  207. 

Marrons  in  signal  rockets,  369. 

Martello  tower,  rapid  destruction  of  one 
with  rifle  projectiles,  485. 

Masonry,  effect  of  projectiles  on,  480. 

Matchlock,  description  of  the,  274. 

Materials  for  the  fabrication  of  cannon, 
138 ;  for  field  cannon,  181 ;  for  sea- 
coast  carriages,  243  ;  for  artillery  car- 
riages, 261-266;  for  pyrotechny,  344- 
348. 

Materiel  of  artillery,  108. 

Maximum  charge  of  fire-arms,  130. 

Maynard  musket,  description  of,  306. 

Maynard's  primer,  how  made,  350. 

Maynard's  self-priming  percussion  lock, 
297. 

Maynard's  system  of  "  packing  the  joint" 
of  breech-loading  arms,  304. 

"Mealed  powder,"  37  ;  in  pyrotechny, 
345. 

Measure  of  deviation,  460. 

Measures,  for  charges  of  powder,  254. 

Mechanical  principles  determining  initial 
velocities,  384. 

Men's  harness,  258. 

Mercury  densimeter  for  gunpowder,  28. 

Metal  for  cannon,  qualities  desirable  in, 
132 ;  the  various  kinds  used,  138. 

Military  fireworks,  356. 

Mill-cake,  pressing,  24. 

Milling,  in  the  manufacture  of  small-arms, 
324. 

Minie,  form  of  projectile  proposed  by, 
309;  his  rifle  projectile,  311. 

Model,  wooden,  for  moulding  cannon, 
195. 

Models  for  ordnance  materiel,  268. 

Molten  iron  used  for  incendiary  purposes 
{note),  372. 

Momentary  effort  exerted  by  draught- 
horses,  214. 

Mordecai.  Major,  results  of  experiments 
of,  with  gun-cotton,  69 ;  experiments 
of,  on  the  influence  of  length  of  bore, 
129. 

Mortar,  nitre  obtained  from,  12. 

Mortar,  a  term  applied  to  early  cannon, 


INDEX. 


545 


104 ;  ancient,  1 06 ;  characteristics  and 
uses  of,  16 7-;  for  siege  purposes,  186; 
form  of,  adopted  in  1861,  187  ;  spheri- 
cal case-shot,  for,  188 ;  how  proved, 
206  ;  inspection  of,  204 ;  how  pointed, 
442  ;  fire  of,  in  attack  or  defence,  499 ; 
case-shot  fire  of,  in  attack  or  defence, 
501 ;  uncertainty  of  the  fire  of,  from 
shipboard,  504. 

Mortar-fuze,  description  of  the,  361. 

Mortar-platform,  how  constructed,  242. 

Mortar-scraper,  254. 

Mortar-shells,  79 ;  bursting-charge  of, 
355 ;  table  of  times  of  flight  of,  401 ; 
table  of  ranges  of,  401 ;  to  find  the 
initial  velocity  of,  42  i ;  how  fired,  436 ; 
fire  of,  464. 

Mortar-wagon  for  siege  purposes,  240. 

Motion,  equations  of,  406,  409. 

Motion  of  rockets,  95,  96  ;  of  a  projectile 
in  vacuo,  395. 

Mottled  iron,  characteristics  of,  148. 

Mould  for  casting  cannon,  how  formed, 
196. 

Moulding  cannon,  process  of,  195. 

Mountain  ammunition,  351. 

Mountain  cannon,  183. 

Mountain  howitzer,  183  ;  ranges  of,  517. 

Mountain  howitzer  carriage,  requisites 
of,  237  ;  description  of,  238. 

Mountain  shells,  range  of,  463. 

Mountings  of  portable  fire-arms,  300 ; 
inspection  of,  330. 

Mountings  of  rifle-musket,  how  cleaned, 
334. 

Movable  pieces  of  fireworks,  378. 

Mules  as  pack-animals,  213. 

Multipliers,  tables  of,  505. 

Musket,  introduced  by  Charles  V,  274; 
description  of  Maynard's,  306 ;  boxes 
for  packing,  330. 

Musket-barrels,  how  made,  321 ;  how 
browned,  327  ;  defects  in,  337  ;  dur- 
ability of,  339  ;  strength  of,  340. 

Mutzig,  trials  made  at,  as  to  the  strength 
.  of  musket-barrels,  340. 

Muzzle  of  cannon,  116;  enlargement  of, 
210. 

Nail-ball,  75. 

Napoleon  field-gun,  description  of,  182 ; 
advantages  and  disadvantages  of,  183. 

Natural  angle  of  sight,  116,  181;  of  siege- 
mortars,  187. 

Natural  line  of  sight  on  cannon,  how 
marked,  207. 

Natural  point-blank,  definition  of,  438. 

Natural  steel,  140. 

Nave-box  of  the  artillery  carriage,  227. 

Navez,  Captain,  ballistic  machine  of,  389. 

Neck  of  cannon,  115. 
35 


Newton  on  the  path  of  projectiles,  382. 

Night-firing,  444. 

Nitrate  of  soda,  15. 

Nitre,  preservation  of,  12 ;  refining  of, 
12  ;  for  laboratory  use,  344. 

Nitre-beds,  how  made,  11. 

Nomenclature  of  artillery  carriages,  225; 
of  cannon  of  old  pattern,  114 ;  of  artil- 
lery carriage- wheels,  220  ;  of  portable 
fire-arms,  291 ;  of  a  percussion  lock, 
296. 

Oak,  effect  of  projectiles  on,  474,  481. 

Objects,  distance  of,  how  estimated,  446. 

Oblong  bullet,  description  of,  used  in  the 
United  States  service,  77. 

Oblong  projectiles,  superiority  of,  74; 
trajectory  of,  423  ;  deviation  of,  431. 

Offensive  and  defensive  fireworks,  376. 

Ordnance  and  ordnance  stores,  what  con- 
stitute, 108. 

Ores  of  iron,  used  for  the  manufacture  of 
cannon,  146. 

Ornamental  fireworks,  376. 

Pack-horse,  work  of,  to  be  regulated,  212. 
Packing    gunpowder,    30 ;    arms,    330 ; 

small-arm  cartridges,  349. 
"Packing   the  joint"  of  breech-loading 

arms,  302. 
Painting  artillery  carriages,  268. 
Paper,  laboratory,  classes  of,  347. 
Paper  shells,  how  made,  380. 
Parrott  rifle-gun,  how  constructed  (note), 

150 ;  how  mounted  (note),  234 ;  ranges 

of,  522. 
Parrott's  rifle  projectile,  535. 
Pass-box,  for  carrying  cartridges,  252. 
Patch,  mode  of  using  with  rifles,  308. 
Pattern  for  moulding  cannon,  195. 
Pendulum  hausse,  how  used,  255. 
Penetration  of  projectiles,  476;  of  the 

rifle-musket  bullet,  486. 
Percussion  bullets,  how  made,  83. 
Percussion  caps,  description  of,  350. 
Percussion  fuze,  description  of,  365. 
Percussion  lock,  nomenclature  of,  296. 
Perriere,  an  early  form  of  cannon,  105. 
Petard,  explosive,  thrown  aside,  376. 
■Petard,  in  ornamental  fireworks,  377. 
Petronel,  description  of  the,  274. 
Pig-iron,  character  of,  146 ;  density  and 

tenacity  of,  147. 
Pike,  the  ancient,  270. 
Piling  of  cannon-balls,  93. 
Pintle,  the  centre  of  the  chassis  of  sea- 
coast  gun-carriages,  246. 
Pintle-hook  of  the  field-limber,  232. 
Pistol,  when  and  where  invented,  274. 
Pistol-carbine,  description  of,  318. 
Pistol  cartridge,  how  made,  350. 


546 


INDEX. 


Pitch  in  pyrotechny,  347. 

Pitched  fascines,  for  incendiary  purposes, 
374. 

Plane  of  fire,  definition  of,  437. 

Plane  of  rupture  of  shells,  84. 

Plane  of  sight,  definition  of,  437. 

Platforms  of  siege  pieces,  how  construct- 
ed, 241. 

Plunging-fire,  459. 

Point-blank,  definition  of,  437. 

Pointing  fire-arms,  435. 

Pointing  guns,  implements  for,  254. 

Pointing  small-arms,  445. 

Pole  of  the  field-limber,  231. 

Polishing  a  sword-blade,  289 ;  small- 
arms,  325. 

Poplar,  charcoal  for  gunpowder  made 
from,  15. 

Portable  fire-arms,  290  ;  early  history  of, 
273  ;  calibre  of,  293. 

Port-fires,  composition  of,  359. 

Position  of  the  centre  of  gravity  of  pro- 
jectiles, 178. 

Pot  of  signal-rockets,  367. 

Potassa,  chlorate  of,  used  in  the  manu- 
facture of  gunpowder,  14;  in  pyro- 
techny, 344. 

Powder,  proper  charge  of,  for  elongated 
bullets,  314;  see  Gunpowder. 

Powder,  round,  25. 

Powder-proof  of  cannon,  205. 

Practical  rule  for  initial  velocity,  387. 

Prairie  artillery  carriage,  description  of, 
238. 

Prairie-cannon,  183. 

Precaution  in  using  fire-arms,  336;  against 
accidents  in  pyrotechny,  343  ;  in  load- 
ing cannon,  435. 

Preponderance  of  cannon,  161 ;  mortars 
and  columbiads  now  made  without 
(note),  162;  of  the  siege-howitzer,  186. 

Preservation  of  gunpowder.  34 ;  of  can- 
non-balls, 93 ;  of  artillery  harness,  219; 
of  artillery  carriages,  259 ;  of  timber, 
265 ;  of  arms  in  service,  332. 

Pressure  in  the  bore  of  the  15-inch  col- 
umbiad,  532. 

Priming-wire,  for  pricking  cartridges, 
253. 

Pritchett  bullet,  how  made,  313. 

Projectile  arms,  ancient,  271. 

Projectile  force  of  gun-cotton,  69. 

Projectiles,  materials  of,  71 ;  advantages 
of  spherical,  73  ;  centre  of  gravity  of, 
74 ;  oblong,  superiority  of  the  form  of, 
74 ;  solid,  for  what  purposes  adapted, 
75 ;  fabrication  of,  88 ;  hollow,  cavi- 
ties of,  how  made,  89 ;  inspection  of, 
90  ;  maximum  velocity  of,  on  what  de- 
pendent, 129;  proportion  of,  to  weight 
of  charge,  131 ;  with  flanges,  for  rifles, 


168;  constructed  on  an  expanding 
principle,  169;  effect  of  length  of,  175; 
influence  of  the  resistance  of  the  air 
upon,  177;  effect  of  the  position  of  the 
centre  of  gravity  of,  178;  shells  and 
hot-shot  the  best  for  sea-coast  bat- 
teries, 189;  injuries  to  cannon  from, 
209 ;  for  small-arms,  307  ;  of  the  Whit- 
worth  rifle,  311 ;  initial  velocity  of, 
383  ;  fall  of,  in  the  air,  404 ;  theory  in 
relation  to  the  form  of,  409 ;  oblong, 
trajectory  of,  423  ;  deviation  of,  424 ; 
concentric,  effect  of  rotation  on,  427  ; 
eccentric,  effect  of  rotation  on,  427 ; 
oblong,  deviation  of,  431 ;  smaller 
than  the  bore,  how  used,  435  ;  effects 
of,  471 ;  of  the  Armstrong  gun,  528. 

Projections,  omitted  on  the  surface  of 
cannon  of  late  construction,  160. 

Prolonge,  a  stout  hempen  rope,  258. 

Proof  of  gunpowder,  27  ;  of  cannon,  205  ; 
of  sword-blades,  289 ;  of  scabbard, 
290. 

Properties  of  bronze,  139;  of  steel,  142. 

Props  of  chassis  rails,  247. 

Puddled  steel,  how  obtained,  142. 

Pulverizing  charcoal,  23. 

Pyrotechny,  definition  of,  342 ;  buildings 
for,  342  ;  precautions  against  accidents 
in,  343  ;  materials  for,  344-348. 

Pyroxile,  or  gun-cotton,  68. 

Quadrant,  gunner's,  256. 
Queen  Anne's  pocket-piece,  106. 
Quick-match,  description  of,  359. 

Rail  platform,  how  constructed,  242. 

Rammer-head  used  in  the  inspection  of 
cannon,  201. 

Rammer-head  for  loading  cannon,  251 

Rampart  grenade,  79. 

Ramrods  of  portable  fire-arms,  301 ;  in- 
spection of,  329. 

Range,  to  determine,  422 ;  definition  of, 
439. 

Range  of  field  artillery,  462,  463,  488 ; 
of  siege-cannon,  493 ;  of  the  Arm- 
strong projectile,  530 ;  of  artillery, 
516-523. 

Ranges,  table  of  values  for  calculation  of, 
507,  513. 

Ranges  of  mortar-shells,  table  of,  401. 

Ranges  obtained  with  Captain  Rodman's 
15-inch  columbiad,  532. 

Rapidity  of  fire,  448. 

Rear-sight  of  portable  fire-arms,  299 ; 
aiming  without,  300. 

Rear-sights,  graduation  of,  445. 

Recoil,  increase  of,  greater  than  increase 
of  charge,  130 ;  diminished  by  appli- 
cation of  weights,  137. 


INDEX. 


547 


Reinforce  of  cannon,  115. 

Rejected  cannon,  how  marked,  207. 

Repairs  of  artillery  carriages,  259. 

Resistance  of  the  air,  402  ;  effect  of,  on 
a  rifle-projectile,  177  ;  loss  of  velocity 
by,  406. 

Retempering  a  sword-blade,  288. 

Ricochet  fire,  450 ;  when  used,  452 ; 
practical  rules  for,  453  ;  of  field  artil- 
lery, 492  ;  of  sea-coast  batteries,  504. 

Ricochet  firing,  cartridge  bag  for,  354. 

Rifle-cannon,  hardness  of  metal  neces- 
sary to,  137 ;  definition  of,  167 ; 
breaching  with,  485. 

Rifled  fire-arms,  form  of  groove  of,  171 ; 
variable  groove  of,  172;  limit  of  incli- 
nation of  grooves  in,  179. 

Rifle-grooves,  points  to  be  observed  in 
constructing,  294. 

Rifle-guns,  ranges  of,  522. 

Rifle-musket,  description  of  the,  316;  how 
dismounted,  332  ;  trials  of  strength  of, 
340 ;  cartridge,  349 ;  bullet,  penetra- 
tions of,  486. 

Rifle-projectiles,  different  systems  of,  535. 

Rifle  siege-gun,  description  of  (note),  184. 

Rifles,  how  classified,  168;  invention  and 
history  of  the,  275  ;  original  mode  of 
loading,  308;  as  distinguished  from 
the  rifle-musket,  317  ;  American  sport- 
ing, 319. 

Rimbases  of  cannon,  116  ;  description  of, 
162. 

Robins,  elongated  projectiles  proposed 
by,  309  ;  on  the  path  of  projectiles, 
383  ;  deviation  by  rotation  discovered 
by,  431. 

Rockets,  theory  and  construction  of,  94 ; 
motion  of,  95 ;  origin  of  movement  in, 
96;  guidiug  principle  of,  97;  Hale's 
system  for  guiding,  98;  Congreve's  sys- 
tem for  guiding,  99  ;  how  fired,  99  ; 
signal  and  war,  99  ;  form  of  trajectory 
of,  100 ;  effect  of  wind  on  the  trajec- 
tory of,  101 ;  history  of,  102  ;  advan- 
tages claimed  for,  over  cannon,  102 ; 
kinds  used  in  the  United  States  ser- 
vice, 103;  signal,  principal  parts  of, 
366. 

Rodman,  Captain,  experiments  of,  with 
cake-powder  (note),  49 ;  experiments 
of,  in  relation  to  the  density  of  gases 
(note),  58 ;  plan  of,  for  cooling  cannon 
from  the  interior,  136 ;  plan  of,  for  de- 
termining the  force  of  the  charge  in 
fire-arms,  152  ;  experiments  of,  on  the 
force  of  cake  and  grained  powder  (note), 
153  ;  his  formula  for  calculating  the 
exterior  form  of  large  cannon  (note), 
157  ;  great  improvements  of,  in  cast- 
ing large  guns,  531. 


Roller  handspike,  for  new  sea-coast  car- 
riages, 257. 

Rolling  fire,  458. 

Rolling  friction,  223. 

Rolling  musket-barrels,  321. 

Roman  candles,  how  made,  380. 

Rope  matting  impenetrable  to  small-arm 
projectiles,  487. 

Rosin  in  pyrotechny,  347. 

Rotation,  initial  velocity  of,  in  rifle-pro- 
jectiles, 174;  a  principal  cause  of  de- 
viation of  projectiles,  425 ;  effect  of, 
in  producing  deviation,  427;  of  the 
earth,  influence  of,  in  producing  devia- 
tion, 434. 

Round  bullets,  denomination  of,  76. 

Round  powder,  how  made,  25. 

Rules  for  firing  to  effect  a  breach,  484. 

Rules  for  ricochet  fire,  453. 

Rumford,  Count,  experiments  of,  on  the 
combustion  of  gunpowder,  54 ;  eprou- 
vette  used  by,  for  determining  the 
force  of  gunpowder,  55. 

Rupture  of  cannon,  tendency  to,  greatest 
from  tangential  force,  156. 

Rupture  of  shells,  84. 

Sabot,  description  of  the,  351. 

Sabre,  the  ancient,  271;  best  construc- 
tion of  for  handling,  283 ;  description 
of,  284. 

Saddle  of  the  artillery  horse,  218. 

Saltpetre,  description  of,  9 ;  whence  ob- 
tained, 10;  test  of  rough,  13;  test  of 
pure,  14 ;  quantity  of,  in  gunpowder, 
31. 

Sand,  the  best  kind  for  moulding  cannon, 
196. 

Sarissa,  or  Macedonian  lance,  270. 

Sawyer's  rifle-projectile,  536. 

Saxon,  in  movable  fireworks,  379. 

Scabbard,  uses  and  material  of  the,  285  ; 
proof  of,  290. 

Schenck's  rifle-projectile,  536. 

Schonbein,  Prof.,  gun-cotton  discovered 
by,  68. 

Schwartz,  Berthold,  explosive  properties 
of  gunpowder  discovered  by,  36. 

Science  of  gunnery,  382. 

Scratches  in  cannon,  210. 

Screw-jack,  used  in  greasing  carriage 
wheels,  259. 

Sea-coast  ammunition,  353. 

Sea-coast  cannon,  188  ;  various  kinds  of, 
190  ;  rapidity  of  fire  of,  449  ;  employ- 
ment  of,  502. 

Sea-coast  carriages,  classification  of,  243 ; 
various  kinds  of,  247. 

Sea-coast  defence,  fires  advantageous  in, 
503. 

Sea-coast  fuze,  description  of,  363. 


548 


INDEX. 


Sea-coast  gun-carriages,  243. 

Sea-coast  guns,  ranges  of,  519. 

Sea-coast  howitzers,  description  of,  193  ; 
ranges  of,  519. 

Sea-coast  howitzer  shell,  79. 

Sea-coast  mortars,  description  of,  193; 
the  new  (note),  194;  range  of,  521; 
ranges  with  the  13-inch,  523. 

Sea-coast  shells,  range  and  force  of,  464. 

Searcher,  201. 

Seasoning  and  preserving  timber,  265. 

Seat  of  the  charge  of  cannon,  120. 

Second  reinforce,  thickness  of,  158. 

Self-priming  percussion-lock,  Maynard's, 
297. 

Serpents,  in  fireworks,  how  composed, 
368. 

Sharp's  system  of  "  packing  the  joint"  of 
breech-loading  arms,  303. 

Shear-steel,  various  kinds  of,  141. 

Shell-hooks,  254. 

Shell-plug  screw,  253. 

Shells,  material  and  denomination  of,  77; 
spherical,  description  of,  78;  charge 
of  rupture  of,  84 ;  loss  of  gas  by  the 
the  fuze-holes  of,  87 ;  strapped  to 
sabots,  354;  service  bursting-charges 
of,  355 ;  loaded  as  carcasses.  372 ; 
paper,  how  made,  380 ;  French  mor- 
tar, table  of  times  of  flight  of,  401 ; 
force  and  range  of,  463. 

Shod  handspike,  for  mortars,  257. 

Shot,  inspection  of,  90  ;  for  proving  can- 
non, 206 ;  wedged  in  cannon,  how 
drawn  out,  261. 

Shrapnel,  Colonel,  spherical  case-shot 
perfected  by,  82. 

Shrapnel  firing,  465. 

Siege  and  sea-coast  ammunition,  353. 

Siege-cannon,  184;  rapidity  of  fire  of, 
449 ;  employment  of,  493. 

Siege-carriages,  various  kinds  of,  239. 

Siege  gun-carriage,  construction  of,  239. 

Siege-guns,  characteristics  of,  184; 
ranges  of,  518. 

Siege-howitzer,  description  of,  186 ;  fire 
of,  in  attack  or  defence,  497  ;  ranges 
of,  519. 

Siege-mortars,  description  of,  186;  bed, 
how  constructed,  241 ;  ranges  of,  521. 

Siege-shells,  uses  of,  464. 

Sights  of  portable  fire-arms,  298. 

Signal-rockets,  99 ;  principal  parts  of, 
366. 

Signals,  fireworks  for,  366 

Sinope,  destruction  of  the  Turkish  fleet 
at,  by  Russian  shells,  189. 

Skelp  of  a  sword-blade,  287. 

Sky-rockets,  378. 

Sleeves,  gunner's,  254 

Sling,  the  ancient,  271. 


Sling-carts,  wooden  and  iron,  249 

Slow-match,  description  of,  358. 

Small-arm  firing,  469. 

Small-arm  projectiles,  307. 

Small-arms,  classification  of,  268  ;  charge 
of  powder  for,  314;  different  kinds  of, 
316  ;  manufacture  of,  320  ;  inspection 
of,  327;  ammunition  for,  348;  trajec- 
tory of  projectiles  of,  414,  418 ;  rapidi- 
ty of  fire  of,  449  ;  how  pointed,  445. 

Soda,  nitrate  of,  15. 

Solid-shot,  classification  of,  75  ;  penetra- 
tions of,  478  ;  when  broken,  478,  481 

Solid-shot  firing,  462. 

Solubility  of  nitre,  9. 

Sparks  in  fireworks,  how  produced,  346. 

Spherical  case-shot,  description  of,  82  ; 
fabrication  of,  88;  for  mortars,  188; 
late  improvements  in,  466 ;  effect  of, 
from  rifle-cannon,  467. 

Spherical  chamber  of  fire-arms,  123. 

Spherical  projectiles,  advantages  of,  73 

Spherical  shells,  description  of,  78. 

Spiking  cannon,  process  of,  260. 

Spirits  of  turpentine  in  pyrotechny,  347 

Splinter-bar  of  the  field-limber,  231. 

Sponge,  for  cleaning  out  cannon,  251. 

Sponge-bucket,  for  washing  bore  of  can- 
non, 258. 

Spontoon,  or  half-pike,  271. 

Sporting  rifle,  American,  319 

Springfield,  Mass.,  United  States  armory 
at,  320. 

Sprue,  used  in  casting  cannon,  196. 

Stand  of  ammunition,  how  composed, 
351. 

Star-gauge,  200. 

Stars  of  signal  rockets,  367 

Steamer  Princeton,  why  the  large  wrought 
iron  gun  burst  on,  144. 

Steel  as  a  material  for  cannon.  139; 
characteristics  of,  140;  properties  of, 
142  ;  Damascus,  how  made,  287  ;  how 
hardened  and  tempered,  326. 

Steel  plates  and  iron,  comparative  resist- 
ance of,  to  projectiles,  474. 

Stick  of  signal-rockets,  369. 

Stock  of  an  artillery  carriage,  225. 

Stock  of  portable  fire-arms,  298;  defects 
in,  338;  inspection  of,  329. 

Stock  trail  system  of  artillery,  112. 

Stone  mortar,  uses  and  dimensions  of. 
187;  charge  of,  465. 

Stone  projectiles,  71. 

Storage  of  gunpowder,  34;  arms,  331. 

Storehouse  for  artillery  harness,  219. 

Straightening  plates  of  musket-barrels, 
321. 

Straight  sword,  parts  of,  278. 

Strain  upon  cannon,  various  kinds  of, 
154. 


INDEX. 


549 


Strapped  ammunition,  353. 

Strapping  shells  described,  354. 

Straps  of  a  stand  of  ammunition,  352. 

Strength  of  cannon,  effect  of  form  of 
chamber  on,  124. 

Strength  of  material  of  cannon,  132,  134. 

Strength  of  musket-barrels,  340. 

Strength  of  wrought  iron,  143. 

Structure  of  rockets,  94. 

Sulphur,  purification  of,  20 ;  properties 
of,  20  ;  quantity  of.  in  gunpowder,  32  ; 
the  tenacity  of  cast-iron  destroyed  by, 
149  ;  in  pyrotechny,  345. 

Sulphuret  of  antimony  in  pyrotechny, 
345. 

System  of  artillery,  108. 

Swaging,  in  the  process  of  making  mus- 
ket-barrels, 323. 

Sweden,  peculiar  form  of  cast-iron  can- 
non cast  in,  159. 

Swell  of  the  muzzle  of  cannon,  115; 
thickness  of,  159. 

Swiss  service  bullet,  314. 

Sword,  the  ancient,  271. 

Sword,  the  straight,  parts  of,  278. 

Sword-bayonet,  description  and  uses  of 
the,  281. 

Sword-blades,  manufacture  of,  287. 

Table  of  initial  velocities  with  service- 
charges,  387. 

Tables  of  fire,  51 G;  purpose  of,  447. 

Tables  of  multipliers,  505. 

Tangential  strain  upon  cannon,  154. 

Tangent-scale,  how  used  in  pointing 
guns,  255. 

Tar  in  pyrotechny.  347. 

Tar-bucket,  for  carrying  grease,  258. 

Targets,  construction  of.  461. 

Tarred-links,  how  made  and  used,  374. 

Tartaglia  on  the  path  of  projectiles,  382. 

Telescopic  sights  of  fire-arms,  299. 

Temperature,  importance  of,  in  the  manu- 
facture of  charcoal,  17. 

Temperature  of  the  gaseous  products  of 
gunpowder,  54. 

Tempering  steel,  326. 

Tempering  sword-blades,  287. 

Tenacity  of  bronze,  139. 

Tenacity  of  puddled  steel,  142. 

Theory  and  construction  of  rockets,  94. 

Thickness  of  the  metal  of  cannon,  151. 

Thouvenin,  form  of  projectile  proposed 
by,  309. 

Thrusting  arms,  277,  284. 

Thumbstall,  for  closing  vent,  253. 

Tige,  or  spindle,  of  Colonel  Thouvenin, 
310. 

Tilted  steel,  141. 

Timber,  for  artillery  carriages,  261-266; 
seasoning  and  preserving,  265. 


Time-fuze,  description  of,  360. 

Times,  table  of,  for  West  Point  ballistic 
machine,  515. 

Tin,  bronze  cannon  injured  by  the  melt- 
ing of  the,  139. 

Torches,  preparation  and  use  of,  375. 

Tourbillion,  description  of  the,  379. 

Track  of  field  carriages,  233. 

Trail  handspike  for  field  carriages,  256. 

Trajectory  of  rockets,  100 ;  of  projectiles, 
ancient  theory  respecting,  382 ;  in  the 
air,  412-424;  under  high  angles  of 
projection,  420;  of  oblong  projectiles, 
423 ;  true  and  calculated,  423. 

Transportation  of  gunpowder,  35. 

Transverse  strain  upon  cannon,  155. 

Travelling-forge,  description  of,  236. 

Treadwell,  Prof.,  plan  of,  for  combining 
wrought-iron  and  cast-iron  in  cannon, 
150. 

Trees,  selection  of,  for  timber  for  artil- 
lery purposes,  263  ;  defects  of  timber, 
265. 

Trench  cart,  for  use  in  trenches,  251. 

Trigger  of  portable  fire-arms,  300. 

Trituration,  influence  of,  on  the  combus- 
tibility of  charcoal,  19;  effect  of,  on 
the  ingredients  of  gunpowder,  43. 

Trunnion-gauge,  201. 

Trunnion- rule,  201. 

Trunnion-square,  201. 

Trunnions  of  cannon,  115;  description  of, 
160 ;  influence  of  position  of,  on  recoil, 
160;  size  of,  dependent  on  recoil,  160; 
importance  of  position  of,  on  siege  and 
sea-coast  cannon,  162 ;  verification  of 
the  axis  of,  203. 

Trunnions  of  the  siege-howitzer,  186. 

Truck  for  moving  cannon  in  casemates, 
250. 

Truck  handspike,  for  sea-coast  carriages, 
257. 

Tube-pouch,  worn  by  a  cannonier,  252. 

Turning  cannon,  199;  musket-barrels, 
324. 

Turning  of  field-carriages,  232. 

Turpentine  in  pyrotechny,  346. 

Twist,  the  inclination  of  a  rifle-groove, 
171. 

Uniform  groove  in  rifled  fire-arms,  171. 
United  States  service  bullet,  312. 
Unspiking  cannon,  process  of,  261. 
Uses  to  which  cannon  are  applied,  180. 

Valiere's  system  of  artillery,  110. 
Values,  tables  of,  510-514. 
Variable  groove  in  rifled  fire-arms,  172. 
Vauban's  method  of  breaching  walls,  482. 
Velocities  and  times,  tables  of  values  of, 
129,  512. 


550 


INDEX. 


Velocity,  initial,  of  projectiles,  383 ;  maxi- 
mum of,  dependent  on  what,  129 ;  loss 
of,  by  resistance  of  the  air,  406 ;  causes 
affecting,  424. 

Velocity  of  combustion  of  gunpowder,  39. 

Venice  turpentine  in  pyrotechny,  347. 

Vent,  small  loss  of  force  by  the  escape 
of  gas  through,  119  ;  table  illustrating 
influence  of  position  of,  119. 

Vent  of  Armstrong  gun,  528. 

Vent  of  cannon,  position  of,  117;  size 
of,  117;  how  bored  200;  inspection 
of,  .204;  wear  of,  how  obviated,  208. 

Vent  of  fireworks,  358. 

Vent  of  rockets,  95. 

Vent-gauges,  201. 

Vent-piece,  copper,  adopted  for  rifle-guns 
(note),  117. 

Vent-searcher,  201. 

Vertical  field  of  fire  of  field-guns,  181 ; 
of  siege-guns,  185 ;  of  siege-mortars, 
187  ;  of  the  new  columbiad,  192. 

Wade,  Major,  experiments  of,  with  eccen- 
tric shells,  430. 

"Wads  (junk,  hay  and  ring),  how  used, 
355. 

"Wagon,  battery,  236. 

"War-club,  ancient,  270. 

"War-powder,  proportions  of  ingredients 
of,  in  the  United  States  service,  53. 

War-rockets,  99. 

"Water,  penetration  of  projectiles  into, 
480. 

"Watering  bucket,  artillery,  258. 

"Weapons,  ancient  defensive,  272. 

"Weight,  recoil  diminished  by,  137. 

Weight  of  American  small-arms,  316- 
319. 

"Weight  of  barrel  of  portable  fire-arms, 
291. 


"Weight  of  cannon,  how  determined,  165. 

Weight  of  field-guns  and  howitzers,  180. 

Weight  of  projectile  and  powder  of 
American  small-arms,  316-319. 

Weight  of  siege-guns,  185. 

Welding,  description  of  the  process  of, 
321. 

"Welding  plates  for  musket-barrels,  321. 

"West  Point  ballistic  machine,  390-395; 
table  of  times  calculated  for,  515. 

Wheels  of  artillery  carriages,  names  of 
parts  of,  220;  objects  of,  221;  influ- 
ence of  size  of,  224;  greased  and  un- 
greased,  227;  should  be  of  the  same 
height,  233. 

"Wheels  of  gun-carriages,  weight  of,  224; 
should  be  few  kinds  of,  224. 

White  iron,  characteristics  of,  14  8. 

White  pine,  effect  of  projectiles  on,  475. 

Whitworth  rifle,  method  of  loading,  311. 

Willow,  charcoal  for  gunpowder  made 
from,  15. 

Wind,  deviation  caused  by,  433 ;  effect 
of,  on  the  trajectory  of  rockets,  101. 

Windage,  loss  offeree  from,  124. 

Wood,  effect  of  projectiles  on,  474 ;  pene- 
trations of  projectiles  into,  479. 

Wootz,  a  natural  steel  from  India,  140. 

Worm,  for  withdrawing  cartridges,  252. 

Wounds  made  by  thrusting-swords,  279. 

Wrought-iron,  projectiles  of,  72;  as  a 
material  for  cannon,  143 ;  for  artillery 
carriages,  266;  effect  of  projectiles  on, 
472. 

Wrought-iron  cannon  made  by  the  Phoe- 
nix Iron  Co.  (note),  144. 

Yataghan  of  the  Arabs,  283. 

Zorndorf,  effect  of  a  field-cannon  ball  at 
the  battle  of,  487. 


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